MSSQL Query method

1. Simple query

1.1 Querying all columns

Example:select * from T_userinfo

1.2 Query Development columns

Example:select * from Username,password to T_userinfo

1.3 Querying for columns with calculations

Example:select age*15 from T_userinfo

2. Conditional query

1. Comparison operators

>, >=, =, <=, <, <>,!>,!< size comparison

Select age from T_userinfo where age<=30 and age>0

2. Range operator

SELECT * from T_userinfo where age between 1 and 30

3. List operators

SELECT * from T_userinfo where type in (' Premium Member ', ' Platinum Member ')//Query membership level is premium and platinum SELECT * from T_userinfo where type not in (' ordinary member ')// Query is not a regular member

4. Logical operators

SELECT * from T_userinfo where age>20 and type= ' Advanced members ' select * from T_userinfo where age>20 and type in (' Premium member ')

5. Null value operator

SELECT * FROM T_userinfo where username are nullselect * from T_userinfo where username are not null

6. Pattern operators

% matches any type and length of characters. For example a%, which represents a string of any length beginning with a

_ matches any single character. For example, A_b, a string with a length of 3 that begins with a and ends with B

[] User-specified range, for example [A-h], representing any single character within the A~h range

[^] User-specified range, for example [^a~h], representing any single character outside of the A~h range

SELECT * FROM T_userinfo where username like '% yuan% ' select * from T_userinfo where username like ' a____ '//query with a letter beginning with a length of 5. such as admin

MSSQL Query method