Sql 如何利用if语句的结果

我这里有三张清单。如果要对列表1和3或列表2和3进行条件组合，在使用以下代码时似乎还可以

declare @Condition varchar(10) = NULL

if @Condition IS NULL
    select * from List1
else 
    select * from List2
union 
select * from List3

但是，如果我想通过将最终结果插入表来存储它们，它将返回If语句的语法错误。有更好的办法吗

declare @Condition varchar(10) = NULL

declare @CombiList table (Value varchar(10))
insert into @CombiList

if @Condition IS NULL
    select * from List1
else 
    select * from List2
union 
select * from List3

---

您需要为每个条件创建两个单独的

INSERT

语句：

if @Condition IS NULL
    insert into @CombiList
        select * from List1
else 
    insert into @CombiList
        select * from List2
        union 
        select * from List3

---

您需要为每个条件创建两个单独的

INSERT

语句：

if @Condition IS NULL
    insert into @CombiList
        select * from List1
else 
    insert into @CombiList
        select * from List2
        union 
        select * from List3

像这样

INSERT INTO @CombiList
SELECT *
FROM   list1
WHERE  @Condition IS NULL
UNION
SELECT *
FROM   List2
WHERE  @Condition IS NOT NULL
UNION
SELECT *
FROM   List3
WHERE  @Condition IS NOT NULL

像这样

INSERT INTO @CombiList
SELECT *
FROM   list1
WHERE  @Condition IS NULL
UNION
SELECT *
FROM   List2
WHERE  @Condition IS NOT NULL
UNION
SELECT *
FROM   List3
WHERE  @Condition IS NOT NULL

---

如果您真正的问题涉及更复杂的语句，并且代码可以包装在存储过程中，那么构建和执行动态

T-SQL

语句可以降低代码的复杂性

例如：

DECLARE @DynamicTSQLStatement NVARCHAR(MAX);

...

-- some statements that are executing always
SET @DynamicTSQLStatement = '....'

-- conditions

IF ... 
   SET @DynamicTSQLStatement = @DynamicTSQLStatement + '.....'
ELSE
   ...
   SET @DynamicTSQLStatement = @DynamicTSQLStatement + '.....'

EXEC sp_executesql @DynamicTSQLStatement

---

如果您真正的问题涉及更复杂的语句，并且代码可以包装在存储过程中，那么构建和执行动态

T-SQL

语句可以降低代码的复杂性

例如：

DECLARE @DynamicTSQLStatement NVARCHAR(MAX);

...

-- some statements that are executing always
SET @DynamicTSQLStatement = '....'

-- conditions

IF ... 
   SET @DynamicTSQLStatement = @DynamicTSQLStatement + '.....'
ELSE
   ...
   SET @DynamicTSQLStatement = @DynamicTSQLStatement + '.....'

EXEC sp_executesql @DynamicTSQLStatement

---

您需要创建两个独立的

INSERT

语句您需要创建两个独立的

INSERT

语句