使用WHERE-ON-internal连接正确的顺序和语法正确地查询MySQL
只是尝试使用连接并找出查询的最佳用法和公式。试着把所有的宠物都给主人——我要用比较来称呼加入吗使用WHERE-ON-internal连接正确的顺序和语法正确地查询MySQL,mysql,inner-join,where-clause,Mysql,Inner Join,Where Clause,只是尝试使用连接并找出查询的最佳用法和公式。试着把所有的宠物都给主人——我要用比较来称呼加入吗 SELECT * FROM VISITOR INNER JOIN OWNER ON VISITOR.OWNER_ID = 1 AND OWNER.ID = 1 或者,我是否调用完全联接并添加WHERE语句 SELECT * FROM VISITOR INNER JOIN OWNER ON VISITOR.OWNER_ID = OWNER.ID WHERE VISITOR.OWNER_ID =1 对
SELECT *
FROM VISITOR
INNER JOIN OWNER ON VISITOR.OWNER_ID = 1
AND OWNER.ID = 1
或者,我是否调用完全联接并添加WHERE语句
SELECT *
FROM VISITOR
INNER JOIN OWNER ON VISITOR.OWNER_ID = OWNER.ID
WHERE VISITOR.OWNER_ID =1
对于正确方法的任何解释也将不胜感激。
谢谢大家:)查询时,通常会基于表到表关系字段进行联接。此外,还可以在相应级别添加其他条件,以进一步筛选最终数据集。也就是说
SELECT
*
FROM
VISITOR V
INNER JOIN OWNER Own
ON V.OWNER_ID = Own.OWNER_ID
WHERE
V.OWNER_ID = 1
确保您在visitor表的“owner_id”键上有一个索引,以帮助优化。。。或者,您可以将其反转,例如
SELECT
*
FROM
OWNER Own
JOIN VISITOR V
ON Own.OWNER_ID = V.OWNER_ID
WHERE
Own.OWNER_ID = 1
@KDawg,对不起,是的,您确实需要“ON”条款