Question

I have a user function that returns a BIT calle dbo.IsPartReady. I am trying to use the function inside of a trigger as follows:

SET @railReady = dbo.IsPartReady(1,@curPartiId);
SET @frameReady = dbo.IsPartReady(2,@curPartiId);
SET @dryAReady = dbo.IsPartReady(3,@curPartiId);
SET @dryBReady = dbo.IsPartReady(4,@curPartiId);

IF ( (@railReady AND @frameReady ) OR ( @dryAReady AND @dryBReady ) )

I m getting the following error in the IF statement: An expression of non-boolean type specified in a context where a condition is expected, near AND .

我做了什么错误?

Answer 1

BIT data type in SQL Server is not a boolean it is an integer. You have to compare the value of the variable with something to get a boolean expression. BIT can have the value 0, 1 or NULL. http://msdn.microsoft.com/en-us/library/ms177603.aspx

declare @B bit = 1

if @B = 1
begin
  print  Yes 
end

Answer 2

使用:

IF ((@railReady = 1 AND @frameReady = 1) OR (@dryAReady = 1 AND @dryBReady = 1))

或替代

IF ((@railReady & @frameReady) | (@dryAReady & @dryBReady)) = 1

更多信息:

为了核实这一点,我们可以使用包含四条<代码>bit的所有组合的真相表。价值:

WITH B(x) AS (SELECT CAST(0 AS bit) UNION ALL SELECT CAST(1 AS bit))
, AllSixteenCombinations(a,b,c,d) AS
    (SELECT * FROM B B1 CROSS JOIN B B2 CROSS JOIN B B3 CROSS JOIN B B4)
SELECT a,b,c,d
, CASE WHEN ((a = 1 AND b = 1) OR (c = 1 AND d = 1)) THEN  Y  ELSE  N  END[Logic]
, CASE WHEN ((a & b) | (c & d)) = 1 THEN  Y  ELSE  N  END [Bitwise]
FROM AllSixteenCombinations

产出:

a     b     c     d     Logic Bitwise
----- ----- ----- ----- ----- -------
0     0     0     0     N     N
0     1     0     0     N     N
0     0     1     0     N     N
0     1     1     0     N     N
1     0     0     0     N     N
1     1     0     0     Y     Y
1     0     1     0     N     N
1     1     1     0     Y     Y
0     0     0     1     N     N
0     1     0     1     N     N
0     0     1     1     Y     Y
0     1     1     1     Y     Y
1     0     0     1     N     N
1     1     0     1     Y     Y
1     0     1     1     Y     Y
1     1     1     1     Y     Y

(16 row(s) affected)

友情链接