MySQL 仅从左联接的表中选择一些列
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Select only some columns from a table on a LEFT JOIN
提问by Psyche
Is it possible to select only some columns from a table on a LEFT JOIN?
是否可以在 LEFT JOIN 的表中只选择一些列？
回答by VoteyDisciple
Of course. Just list the columns you want to select as you would in any query:
当然。只需像在任何查询中一样列出您要选择的列：
SELECT table1.column1, table1.column2, table2.column3
FROM table1
LEFT JOIN table2 ON (...)
Note that I've included the table1.or table2.prefix on all columns to be sure there aren't any ambiguities where fields with the same name exist in both tables.
请注意，我在所有列中都包含了table1.ortable2.前缀，以确保两个表中存在同名字段时不会有任何歧义。
回答by flayto
If you want some of table1's columns and some of table2's columns, you would do something like
如果你想要一些 table1 的列和一些 table2 的列，你会做类似的事情
SELECT t1.col1, t1.col2, t1.col3, t2.col1, t2.col2, t2.col3
FROM table1 t1
LEFT JOIN table2 t2
ON...
回答by jlansey
Add a *to just that table in your select statement, separate from other columns with a comma:
*在 select 语句中将a 添加到该表中，用逗号与其他列分开：
SELECT table1.*, table2.col2, table2.col3
FROM table1
LEFT JOIN table2
ON...
