MySQL 中 ROW_NUMBER() 的插入等效函数?
mysqlmysqli database
MySQL 中没有 ROW_NUMBER() 的插入等效函数，但您可以借助变量来实现。语法如下 −
SELECT (@yourVariableName:=@yourVariableName + 1) AS `anyAliasName`, yourColumnName1,yourColumnName2,...N FROM yourTableName ,(SELECT @yourVariableName:=0) AS anyAliasName;
为了理解上述语法，让我们创建一个表。创建表的查询如下 −
mysql> create table RowNumberDemo -> ( -> UserId int, -> UserName varchar(20) -> ); Query OK, 0 rows affected (0.74 sec)
使用 insert 命令在表中插入一些记录。 查询语句如下 −
mysql> insert into RowNumberDemo values(10,'John'); Query OK, 1 row affected (0.14 sec) mysql> insert into RowNumberDemo values(50,'Carol'); Query OK, 1 row affected (0.20 sec) mysql> insert into RowNumberDemo values(100,'Sam'); Query OK, 1 row affected (0.20 sec) mysql> insert into RowNumberDemo values(150,'Mike'); Query OK, 1 row affected (0.54 sec) mysql> insert into RowNumberDemo values(210,'Bob'); Query OK, 1 row affected (0.58 sec)
使用 select 语句显示表中的所有记录。查询如下 −
mysql> select *from RowNumberDemo;
以下是输出 −
+--------+----------+ | UserId | UserName | +--------+----------+ | 10 | John | | 50 | Carol | | 100 | Sam | | 150 | Mike | | 210 | Bob | +--------+----------+ 5 rows in set (0.00 sec)
以下查询用于获取类似于 ROW_NUMBER 的值 −
mysql> SELECT -> (@ROW_NUMBER:=@ROW_NUMBER + 1) AS `ROW_NUMBER`, UserId,UserName -> FROM -> RowNumberDemo,(SELECT @ROW_NUMBER:=0) AS t;
以下是输出 −
+------------+--------+----------+ | ROW_NUMBER | UserId | UserName | +------------+--------+----------+ | 1 | 10 | John | | 2 | 50 | Carol | | 3 | 100 | Sam | | 4 | 150 | Mike | | 5 | 210 | Bob | +------------+--------+----------+ 5 rows in set (0.03 sec)
