用SQL语句处理

create TABLE AA(A INT,B CHAR(20) NULL)

INSERT INTO AA(A,B)VALUES(1,NULL)

INSERT INTO AA(A,B)VALUES(2,'BBBB')

例如: 变量${AAA}的值XXXXX就代表NULL值

SELECT A,B FROM AA WHERE ISNULL(B,'XXXXX')='${AAA}'

变量带入

${AAA}='XXXXX'

SELECT A,B FROM AA WHERE ISNULL(B,'XXXXX')='XXXXX'

结果

1  NULL

${AAA}='BBBB'

SELECT A,B FROM AA WHERE ISNULL(B,'XXXXX')='BBBB'

结果

2 BBBB