我试图使用一个选择语句从某个MySQL表中获得除一个以外的所有列。有什么简单的方法吗?
编辑:在这个表格中有53列(不是我的设计)
我试图使用一个选择语句从某个MySQL表中获得除一个以外的所有列。有什么简单的方法吗?
编辑:在这个表格中有53列(不是我的设计)
当前回答
(不要在大桌子上尝试,结果可能是……令人惊讶的!)
临时表
DROP TABLE IF EXISTS temp_tb;
CREATE TEMPORARY TABLE ENGINE=MEMORY temp_tb SELECT * FROM orig_tb;
ALTER TABLE temp_tb DROP col_a, DROP col_f,DROP col_z; #// MySQL
SELECT * FROM temp_tb;
DROP语法可能因数据库而异
其他回答
也许我有一个解决Jan Koritak指出的矛盾的方法
SELECT CONCAT('SELECT ',
( SELECT GROUP_CONCAT(t.col)
FROM
(
SELECT CASE
WHEN COLUMN_NAME = 'eid' THEN NULL
ELSE COLUMN_NAME
END AS col
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'employee' AND TABLE_SCHEMA = 'test'
) t
WHERE t.col IS NOT NULL) ,
' FROM employee' );
表:
SELECT table_name,column_name
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'employee' AND TABLE_SCHEMA = 'test'
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
table_name column_name
employee eid
employee name_eid
employee sal
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
查询结果:
'SELECT name_eid,sal FROM employee'
Mahomedalid发布的答案有一个小问题:
在替换函数代码中替换“<columns_to_delete>,”用“”,如果要替换的字段是concat字符串中的最后一个字段,那么这个替换会有一个问题,因为最后一个字段没有字符逗号“,”并且没有从字符串中删除。
我的建议:
SET @sql = CONCAT('SELECT ', (SELECT REPLACE(GROUP_CONCAT(COLUMN_NAME),
'<columns_to_delete>', '\'FIELD_REMOVED\'')
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = '<table>'
AND TABLE_SCHEMA = '<database>'), ' FROM <table>');
替换<表>,<数据库>和'
在我的情况下,被删除的列被字符串“FIELD_REMOVED”所取代,这是因为我试图安全内存。(我正在删除的字段是一个大约1MB的BLOB)
我同意列出所有列的“简单”解决方案,但这可能会造成负担,而且打字错误可能会浪费大量时间。我使用“getTableColumns”函数检索适合粘贴到查询中的列的名称。然后我要做的就是删除我不想要的。
CREATE FUNCTION `getTableColumns`(tablename varchar(100))
RETURNS varchar(5000) CHARSET latin1
BEGIN
DECLARE done INT DEFAULT 0;
DECLARE res VARCHAR(5000) DEFAULT "";
DECLARE col VARCHAR(200);
DECLARE cur1 CURSOR FOR
select COLUMN_NAME from information_schema.columns
where TABLE_NAME=@table AND TABLE_SCHEMA="yourdatabase" ORDER BY ORDINAL_POSITION;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
OPEN cur1;
REPEAT
FETCH cur1 INTO col;
IF NOT done THEN
set res = CONCAT(res,IF(LENGTH(res)>0,",",""),col);
END IF;
UNTIL done END REPEAT;
CLOSE cur1;
RETURN res;
您的结果返回一个以逗号分隔的字符串,例如…
col1, col2 col3 col4, ... col53
这个问题是关于MySQL的,但我仍然认为值得一提的是,至少谷歌BigQuery和H2原生支持* EXCEPT语法。
SELECT * FROM actor
生产:
|actor_id|first_name|last_name |last_update |
|--------|----------|------------|-----------------------|
|1 |PENELOPE |GUINESS |2006-02-15 04:34:33.000|
|2 |NICK |WAHLBERG |2006-02-15 04:34:33.000|
|3 |ED |CHASE |2006-02-15 04:34:33.000|
而
SELECT * EXCEPT (last_update) FROM actor
生产:
|actor_id|first_name|last_name |
|--------|----------|------------|
|1 |PENELOPE |GUINESS |
|2 |NICK |WAHLBERG |
|3 |ED |CHASE |
也许,MySQL的未来版本也会支持这种语法?
如果你使用MySQL工作台,你可以右键单击你的表,点击发送到sql编辑器,然后选择所有语句,这将创建一个所有字段都被列出的语句,如下所示:
SELECT `purchase_history`.`id`,
`purchase_history`.`user_id`,
`purchase_history`.`deleted_at`
FROM `fs_normal_run_2`.`purchase_history`;
SELECT * FROM fs_normal_run_2.purchase_history;
现在你可以删除那些你不想要的。