Question

我在SQL Server中编写了以下函数：

ALTER FUNCTION dbo.fnFormatMessage 
    (@Message varchar(max), @Thought varchar(max))
RETURNS varchar
BEGIN
    DECLARE @FinalMessage AS varchar(max) = ' '

    SELECT
        @FinalMessage = LTRIM(RTRIM(CASE WHEN LEN(RTRIM(LTRIM(CONVERT(VARCHAR(MAX),ISNULL(@Thought,''))))) > 0 THEN
                                CASE WHEN SUBSTRING(CONVERT(VARCHAR(MAX), ISNULL(@Message,'')), LEN(CONVERT(VARCHAR(MAX), ISNULL(@Message,''))) , 1) IN ('?','!', '.')THEN
                                    CONVERT(VARCHAR(MAX), ISNULL(@Message,''))
                                ELSE 
                                    CONVERT(VARCHAR(MAX), ISNULL(@Message,''))
                                END
                            + CHAR(13) + CHAR(13) + CHAR(10) +'My Thoughts: ' + CHAR(13) 
                            + CASE WHEN SUBSTRING(CONVERT(VARCHAR(MAX), ISNULL(@Thought,'')), LEN(CONVERT(VARCHAR(MAX), ISNULL(@Thought,''))) , 1) IN ('?','!', '.') THEN
                                CONVERT(VARCHAR(MAX), ISNULL(@Thought,''))
                            ELSE 
                                CONVERT(VARCHAR(MAX), ISNULL(@Thought,'')) + '.'
                            END
                    ELSE
                        CASE WHEN SUBSTRING(CONVERT(VARCHAR(MAX), ISNULL(@Message,'')), LEN(CONVERT(VARCHAR(MAX), ISNULL(@Message,''))) , 1) IN ('?','!', '.') OR 
                                                                                                                        CONVERT(VARCHAR(MAX), ISNULL(@Message,'')) = ''
                        THEN
                                CONVERT(VARCHAR(MAX), ISNULL(@Message,''))
                        ELSE 
                                CONVERT(VARCHAR(MAX), ISNULL(@Message,'')) + '.'
                        END 
                END)) 
                Return @FinalMessage
    END

当我将其作为

运行时

 Select dbo.fnFormatMessage('This is a message', 'This is my thought')

我期待低于输出：

This is a message
My Thought: This is my thought

但它只返回T

Answer 1

将RETURNS varchar更改为RETURNS varchar(8000)或适当的长度。始终使用明确的长度VARCHAR

SQL Server函数不生成预期输出

1 个答案: