Question

我有以下2种SQL语法，我希望将它们合并为1种SQL语法

SELECT sentFrom 
FROM tableName 
WHERE id = :varid 
AND sentFrom != :vartext

SELECT sentTo 
FROM tableName 
WHERE id = :varid 
AND sentTo != :vartext

我想我应该举个例子：

MYSQL表

-----------------------------------
sentFrom          sentTo
1                 2
1                 3
2                 1
2                 3

查询

select sentFrom where sentFrom != 1 and select sentTo where sentTo != 1

返回：

已发送2但未发送从1

已发送至3但未从1发送

sentFrom 2但未发送到1

sentFrom 2和sentTo 3

Answer 1

  Syntex of select query is :
 Select Colname1,Colname2,.... from tablename 
        where colname=value and/or ...
        group by cond..
        having cond...
        order by colname, colname asc/desc
======================================
Ex:

  SELECT sentFrom,sentTo  FROM tableName
       WHERE id = :varid AND (sentFrom != :vartext or sentTo != :vartext)

Answer 2

我认为这应该有所帮助。

SELECT a.sentFrom , b.sentTo FROM 
 (SELECT id, sentFrom FROM tableName WHERE id = :varid AND sentFrom != :vartext) a
JOIN 
 (SELECT id, sentTo FROM tableName WHERE id = :varid AND sentTo != :vartext) b
ON a.id = b.id;

如果您认为ID在每个查询中选择的行中不常见，请删除连接条件ON a.id = b.id。在这种情况下，它将返回查询1的Cartesian product个记录来查询2.

MYSQL仅选择field1，field2，其中field1或field2不等于text

2 个答案: