在 sql 中使用嵌套 IF ELSE 语句

Question

当满足以下任何一个条件时，我希望代码进入下一个执行步骤：

1. 名字、姓氏和出生日期：三者均不为空
2. ID 和 DOB 不为空
3. SSN 和 DOB 不能为空
4. ID和组号不能为空

下面是我的代码。当我通过提供名字、姓氏和出生日期（满足条件 1）来运行它时，它仍然失败，说不满足条件 4。有人可以告诉我我做错了什么吗？

IF ( ( @FirstName IS NULL 
        OR Len(Ltrim(@FirstName)) = 0 ) 
     AND ( @LastName IS NULL 
            OR Len(Ltrim(@LastName)) = 0 ) 
     AND ( @DOB IS NULL ) ) 
  BEGIN 
      INSERT INTO @ValidationError 
                  (errormessage) 
      VALUES      ( 'first name, last name and Date of Birth must be specified.' 
      ) 
  END 
ELSE 
  BEGIN 
      IF ( @DOB IS NULL 
           AND @Id IS NULL ) 
        BEGIN 
            INSERT INTO @ValidationError 
                        (errormessage) 
            VALUES      ( 'Date of Birth and Id must be specified.' ) 
        END 
      ELSE 
        BEGIN 
            IF ( @DOB IS NULL 
                 AND @SSN IS NULL ) 
              BEGIN 
                  INSERT INTO @ValidationError 
                              (errormessage) 
                  VALUES      ( 'Date of Birth and SSN must be specified.' ) 
              END 
            ELSE 
              BEGIN 
                  IF ( @Id IS NULL 
                       AND @GroupNumber IS NULL ) 
                    BEGIN 
                        INSERT INTO @ValidationError 
                                    (errormessage) 
                        VALUES      ( 'Id and Group Number must be specified.' ) 
                    END 
              END 
        END 
  END 

Answer 1

声明CASE会更简单：

INSERT INTO @ValidationError  (errormessage)  
SELECT CASE WHEN Criteria1 THEN 'first name, last name and Date of Birth must be specified.'
            WHEN Criteria2 THEN 'Date of Birth and Id must be specified.'
            WHEN Criteria3 THEN 'Date of Birth and SSN must be specified.'  
            WHEN Criteria4 THEN 'Id and Group Number must be specified.'        
       END

至于语法中的错误，您有无关的BEGIN和END，我相信以下内容会起作用：

IF ( ( @FirstName IS NULL OR Len(Ltrim(@FirstName)) = 0 ) 
     AND ( @LastName IS NULL OR Len(Ltrim(@LastName)) = 0 ) 
     AND ( @DOB IS NULL ) ) 
    BEGIN 
          INSERT INTO @ValidationError 
                      (errormessage) 
          VALUES      ( 'first name, last name and Date of Birth must be specified.') 
    END 
ELSE IF ( @DOB IS NULL AND @Id IS NULL ) 
    BEGIN 
        INSERT INTO @ValidationError 
                    (errormessage) 
        VALUES      ( 'Date of Birth and Id must be specified.' ) 
    END 
ELSE IF ( @DOB IS NULL AND @SSN IS NULL ) 
    BEGIN 
        INSERT INTO @ValidationError 
                    (errormessage) 
        VALUES      ( 'Date of Birth and SSN must be specified.' ) 
    END 
ELSE IF ( @Id IS NULL AND @GroupNumber IS NULL ) 
    BEGIN 
        INSERT INTO @ValidationError 
                    (errormessage) 
        VALUES      ( 'Id and Group Number must be specified.' ) 
    END