mysql – 嵌套的CAST无法正常工作

为什么嵌套的转换不适用于MySQL？ (它确实使用SQL Server)

select cast(cast(myColumn as decimal(5,2)) as int) from myTable 

SQLFiddle Example 最佳答案 根据the manual：

CAST(expr AS type) […]

CONVERT(expr,type) […]

The type can be one of the following values:

• BINARY[(N)]

• CHAR[(N)]

• DATE

• DATETIME

• DECIMAL[(M[,D])]

• SIGNED [INTEGER]

• TIME

• UNSIGNED [INTEGER]

所以,只需按照手册：

SELECT CAST(CAST(myColumn AS DECIMAL(5,2)) AS SIGNED) FROM myTable

要么

SELECT CAST(CAST(myColumn AS DECIMAL(5,2)) AS UNSIGNED) FROM myTable

（编辑：李大同）

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