第二十三章 SQL函數 CAST（二）
轉換位值
可以將expr值轉換為BIT以返回0或1。 如果expr為1或任何其他非零數值，則返回1。 如果expr為“TRUE”、“TRUE”或“TRUE”，則返回1。 (“True”可以用任何大小寫組合表示，但不能縮寫為“T”。) 如果expr是任何其他非數值值，則返回0。 如果expr為0，則返回0。
在下面的例子中，前5個CAST操作返回1，後5個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