SQL函数 CAST

SQL函数 CAST

转换位值

可以将expr值转换为BIT以返回0或1。 如果expr为1或任何其他非零数值，则返回1。 如果expr为“TRUE”、“TRUE”或“TRUE”，则返回1。 (“True”可以用任何大小写组合表示，但不能缩写为“T”。) 如果expr是任何其他非数值值，则返回0。 如果expr为0，则返回0。

在下面的例子中，前5个CAST操作返回1，后5个CAST操作返回0:

SELECT CAST(1 AS BIT) AS One, 
       CAST(7 AS BIT) AS Num,      
       CAST(743.6 AS BIT) AS Frac,  
       CAST(0.3 AS BIT) AS Zerofrac,
       CAST('tRuE' AS BIT) AS TrueWord,
       CAST(0 AS BIT) AS Zero,  
       CAST('FALSE' AS BIT) AS FalseWord, 
       CAST('T' AS BIT) AS T,    
       CAST('F' AS BIT) AS F,   
       CAST(0.0 AS BIT) AS Zerodot

// 输出结果： 1 1 1 1 1 0 0 0 0 0