MySQL Query Çë½Ì

Example code
SQL code:

create table t(idx int,cname varchar(30));
insert into t values(1,'a');
insert into t values(2,'b');
insert into t values(3,'c');




select * from tµÄ½á¹ûÕâÑù
SQL code:

mysql> select * from t;
+------+-------+
| idx | cname |
+------+-------+
| 1 | a |
| 2 | b |
| 3 | c |
+------+-------+




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SQL code:

+------+-------+-------+
| idx | cname |countnum|
+------+-------+-------+
| 1 | a |3 |
| 2 | b |3 |
| 3 | c |3 |
+------+-------+-------+



countnum ÊÇÕâÕűíµÄ×ܼǼÊý

SQL ServerºÍoracle¶¼¿ÉÒÔÓÃRow_numberÀ´µÃµ½£¬
MySQL ÈçºÎµÃµ½£¿

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mysqlûÓÐRow_numberÖ®ÀàµÄº¯Êý£¬Ö»ÓÐͨ¹ý¼ä½Ó·½·¨µÃµ½

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SQL code:
mysql> select t.*,a.countnum
-> from t,(select count(*) as countnum from t) a;
+------+-------+----