如何在MySql中使用AS关键字？

Question

在下面的SP中，我将获得一个单列的结果。如何命名输出列？

    DELIMITER $$

DROP PROCEDURE IF EXISTS `InsGen` $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `InsGen`
(
in_db varchar(20),
in_table varchar(20),
in_ColumnName varchar(20),
in_ColumnValue varchar(20)
)
BEGIN

declare Whrs varchar(500);
declare Sels varchar(500);
declare Inserts varchar(2000);
declare tablename varchar(20);
declare ColName varchar(20);

set tablename=in_table;


# Comma separated column names - used for Select
select group_concat(concat('concat(\'"\',','ifnull(',column_name,','''')',',\'"\')'))
INTO @Sels from information_schema.columns where table_schema=in_db and table_name=tablename;


# Comma separated column names - used for Group By
select group_concat('`',column_name,'`')
INTO @Whrs from information_schema.columns where table_schema=in_db and table_name=tablename;


#Main Select Statement for fetching comma separated table values
set @Inserts=concat("select concat('insert into ", in_db,".",tablename," values(',concat_ws(',',",@Sels,"),');')
from ", in_db,".",tablename, " where ", in_ColumnName, " = " , in_ColumnValue, " group by ",@Whrs, ";");

PREPARE Inserts FROM @Inserts;

EXECUTE Inserts;

END $$

DELIMITER ;

Answer 1

SELECT something AS somename ...

在你的情况下，它是：

SELECT group_concat(concat('concat(\'"\',','ifnull(',column_name,','''')',',\'"\')')) AS myColumnName
INTO @Sels from information_schema.columns where table_schema=in_db and table_name=tablename;

Answer 2

set @Inserts=concat("select concat('insert into ", in_db,".",tablename," values(',concat_ws(',',",@Sels,"),');') as `Inserts` from ", in_db,".",tablename, " where ", in_ColumnName, " = " , in_ColumnValue, " group by ",@Whrs, ";");

PREPARE Inserts FROM @Inserts;

EXECUTE Inserts;

在第一个答案中建议的前两个select语句中添加“AS”语句。

Answer 3

This Worked for me : 

set @Inserts=concat("select concat('insert into ", in_db,".",tablename," values(',concat_ws(',',",@Sels,"),');') as MyColumn from ", in_db,".",tablename, " where ", in_ColumnName, " = " , in_ColumnValue, " group by ",@Whrs, ";");