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默认情况下，SQL选择非空值_Sql_Oracle - Fatal编程技术网
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默认情况下，SQL选择非空值

sql oracle

默认情况下，SQL选择非空值,sql,oracle,Sql,Oracle,我需要一个sql语句，可以在字段不为null时选择行，但如果每个字段都为null，则显示它们 比如： SELECT field1, field2, field3 FROM tableName WHERE field1 = CASE WHEN field1 IS NOT NULL THEN field1 ELSE null END; 示例： 有一张像这样的桌子： ______________________________________ | field1 |

我需要一个sql语句，可以在字段不为null时选择行，但如果每个字段都为null，则显示它们

比如：

SELECT
field1, field2, field3
FROM
tableName
WHERE field1 = 
CASE WHEN field1 IS NOT NULL THEN 
    field1
ELSE
    null
END;
示例：

有一张像这样的桌子：

 ______________________________________
|   field1   |   field2   |   field3   |
 --------------------------------------
|    null    |  TestData  |    123     |
|     23     |  TestData  |    123     |
|    null    |  TestData  |    123     |
 --------------------------------------
结果将是：

 ______________________________________
|   field1   |   field2   |   field3   |
 --------------------------------------
|     23     |  TestData  |    123     |
 --------------------------------------
但如果每个字段1都为空，则数据为：

 ______________________________________
|   field1   |   field2   |   field3   |
 --------------------------------------
|    null    |  TestData  |    123     |
|    null    |  TestData  |    123     |
|    null    |  TestData  |    123     |
 --------------------------------------
它应该显示每一行

请尝试以下操作：

SELECT
field1, field2, field3
FROM
tableName
WHERE (field1 is not null) or 
(field1 is null and field2 is null and field3 is null)
带有数字：

Oracle 11g R2架构设置：

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT CAST( null AS NUMBER(4) ), 'TestData', 123 FROM DUAL
UNION ALL SELECT null,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    123 |
| (null) | TestData |    123 |
| (null) | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 124 FROM DUAL
UNION ALL SELECT null,   'TestData', 124 FROM DUAL
UNION ALL SELECT null, 'TestData', 125 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 124
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 124

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    124 |

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 125
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 125

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    125 |
查询1：

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT CAST( null AS NUMBER(4) ), 'TestData', 123 FROM DUAL
UNION ALL SELECT null,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    123 |
| (null) | TestData |    123 |
| (null) | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 124 FROM DUAL
UNION ALL SELECT null,   'TestData', 124 FROM DUAL
UNION ALL SELECT null, 'TestData', 125 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 124
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 124

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    124 |

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 125
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 125

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    125 |
：

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT CAST( null AS NUMBER(4) ), 'TestData', 123 FROM DUAL
UNION ALL SELECT null,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    123 |
| (null) | TestData |    123 |
| (null) | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 124 FROM DUAL
UNION ALL SELECT null,   'TestData', 124 FROM DUAL
UNION ALL SELECT null, 'TestData', 125 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 124
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 124

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    124 |

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 125
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 125

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    125 |
仅包含空值：

Oracle 11g R2架构设置：

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT CAST( null AS NUMBER(4) ), 'TestData', 123 FROM DUAL
UNION ALL SELECT null,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    123 |
| (null) | TestData |    123 |
| (null) | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 124 FROM DUAL
UNION ALL SELECT null,   'TestData', 124 FROM DUAL
UNION ALL SELECT null, 'TestData', 125 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 124
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 124

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    124 |

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 125
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 125

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    125 |
查询2：

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT CAST( null AS NUMBER(4) ), 'TestData', 123 FROM DUAL
UNION ALL SELECT null,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    123 |
| (null) | TestData |    123 |
| (null) | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 124 FROM DUAL
UNION ALL SELECT null,   'TestData', 124 FROM DUAL
UNION ALL SELECT null, 'TestData', 125 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 124
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 124

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    124 |

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 125
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 125

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    125 |
：

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT CAST( null AS NUMBER(4) ), 'TestData', 123 FROM DUAL
UNION ALL SELECT null,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    123 |
| (null) | TestData |    123 |
| (null) | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 124 FROM DUAL
UNION ALL SELECT null,   'TestData', 124 FROM DUAL
UNION ALL SELECT null, 'TestData', 125 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 124
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 124

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    124 |

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 125
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 125

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    125 |
------编辑-----

Oracle 11g R2架构设置：

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT CAST( null AS NUMBER(4) ), 'TestData', 123 FROM DUAL
UNION ALL SELECT null,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    123 |
| (null) | TestData |    123 |
| (null) | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 124 FROM DUAL
UNION ALL SELECT null,   'TestData', 124 FROM DUAL
UNION ALL SELECT null, 'TestData', 125 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 124
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 124

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    124 |

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 125
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 125

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    125 |
查询1：

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT CAST( null AS NUMBER(4) ), 'TestData', 123 FROM DUAL
UNION ALL SELECT null,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    123 |
| (null) | TestData |    123 |
| (null) | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 124 FROM DUAL
UNION ALL SELECT null,   'TestData', 124 FROM DUAL
UNION ALL SELECT null, 'TestData', 125 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 124
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 124

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    124 |

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 125
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 125

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    125 |
：

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT CAST( null AS NUMBER(4) ), 'TestData', 123 FROM DUAL
UNION ALL SELECT null,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    123 |
| (null) | TestData |    123 |
| (null) | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 124 FROM DUAL
UNION ALL SELECT null,   'TestData', 124 FROM DUAL
UNION ALL SELECT null, 'TestData', 125 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 124
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 124

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    124 |

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 125
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 125

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    125 |
查询2：

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT CAST( null AS NUMBER(4) ), 'TestData', 123 FROM DUAL
UNION ALL SELECT null,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    123 |
| (null) | TestData |    123 |
| (null) | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 124 FROM DUAL
UNION ALL SELECT null,   'TestData', 124 FROM DUAL
UNION ALL SELECT null, 'TestData', 125 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 124
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 124

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    124 |

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 125
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 125

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    125 |
：

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT CAST( null AS NUMBER(4) ), 'TestData', 123 FROM DUAL
UNION ALL SELECT null,   'TestData', 123 FROM DUAL
UNION ALL SELECT null, 'TestData', 123 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  NOT EXISTS ( SELECT 1
                    FROM   test
                    WHERE  field1 IS NOT NULL )
OR     field1 IS NOT NULL

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    123 |
| (null) | TestData |    123 |
| (null) | TestData |    123 |

CREATE TABLE test ( field1, field2, field3 ) AS
          SELECT null, 'TestData', 123 FROM DUAL
UNION ALL SELECT 23,   'TestData', 124 FROM DUAL
UNION ALL SELECT null,   'TestData', 124 FROM DUAL
UNION ALL SELECT null, 'TestData', 125 FROM DUAL;

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 124
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 124

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
|     23 | TestData |    124 |

SELECT field1,
       field2,
       field3
FROM   test
WHERE  (
         NOT EXISTS ( SELECT 1
                      FROM   test
                      WHERE  field1 IS NOT NULL
                      AND    field2 = 'TestData'
                      AND    field3 = 125
                    )
       OR field1 IS NOT NULL
       )
AND field2 = 'TestData'
AND field3 = 125

| FIELD1 |   FIELD2 | FIELD3 |
|--------|----------|--------|
| (null) | TestData |    125 |
请使用示例数据和所需结果编辑您的问题。不清楚，请尝试解释更多您想要实现的目标。看起来您想要
COALESCE（）
，但我不确定我是否了解您的确切规格。。。你能编辑这个问题并提供一个例子吗？这个方法很好，但不能解决我的问题。请看这个例子：当field3=124时，它工作，但如果是125，它就不工作！你让我开心。多谢各位much@JonathanCobo如果其中一个答案是正确的，你可以接受它，这样问题就结束了（如果合适的话，请向上投票）。