如何将列的值分配给变量？

Question

我想将BalanceAmount设置为变量，但它返回一个空值。

Declare BalAmt as int;
SET BalAmt = (SELECT BalanceAmount FROM mstragentrecharge);
SELECT BalAmt

Answer 1

如果此代码来自函数或过程，请尝试以下操作

Declare BalAmt as int;

SELECT BalanceAmount into BalAmt  FROM mstragentrecharge);

SELECT BalAmt

或者，对于简单查询：

SET @BalAmt  := '';
SELECT @BalAmt  := `BalanceAmount ` FROM mstragentrecharge limit 1;
SELECT @BalAmt FROM mstragentrecharge;