sql - SQL User Defined Function Generates a Non-Boolean Type Error

Question

I'm getting this error on a SQL user defined function:

An expression of non-boolean type specified in a context where a condition is expected, near ')'.

For this:

UPDATE LMI_Contact
SET Phone = NULL
WHERE dbo.LMI_IsSingleCharacterRepeated(Phone, '0')

where the function can be created using:

-- ***this will also find NULL and empty string values***
CREATE FUNCTION LMI_IsSingleCharacterRepeated (@string varchar(max), @char char(1))
RETURNS bit
AS 
BEGIN
    DECLARE @index int
    DECLARE @len int
    DECLARE @currentChar char(1)
    SET @index = 1
    SET @len= LEN(@string)

    WHILE @index <= @len
    BEGIN
        SET @currentChar = SUBSTRING(@string, @index, 1)
        IF @currentChar = @char
            SET @index= @index+ 1
        ELSE
            RETURN 0
    END
    RETURN 1
END;
GO

This function is for checking if a string is any specified single character, repeated.

Answer 1

即使返回类型是 ，您也必须对函数使用比较运算符bit。

UPDATE LMI_Contact
SET Phone = NULL
WHERE dbo.LMI_IsSingleCharacterRepeated(Phone, '0') = 1

Answer 2

尝试这个

CREATE FUNCTION LMI_IsSingleCharacterRepeated (@str varchar(max), @char char(1))
RETURNS BIT
AS 
BEGIN
    DECLARE @indx int
    DECLARE @len int
    DECLARE @currentChar char(1)
    SET @indx = 1
    SET @len= LEN(@str)

    WHILE @indx <= @len
    BEGIN
        SET @currentChar = SUBSTRING(@str, @indx, 1)
        IF @currentChar = @char
            SET @indx= @indx+ 1
        ELSE
            RETURN 0
    END
    RETURN 1
END;
GO

Answer 3

您需要将查询的 where 子句修改为：

UPDATE LMI_Contact
SET Phone = NULL
WHERE dbo.LMI_IsSingleCharacterRepeated(Phone, '0') = 1