General conditions of inquiry
- 语法：SELECT col_list FROM table_name WHERE condintion_expression
- Examples: SELECT * FROM games WHERE GNO = 9
- 例子：SELECT *FROM games WHERE score>2500
- 例子：SELECT *FROM users WHERE user_qq=1 AND score>400
- Features: Search conditions are met behind WHERE keyword
- Logical operators: AND, OR, NOT (NOT)
Fuzzy query
- 语法：SELECT *FROM table_name WHERE col_name BETWEEN number1 AND number2
- Features: use BETWEEN, AND keyword query number1 (included) to number2 (including) the range of data
- 例子：SELECT *FROM games WHERE GNO BETWEEN 2 AND 8
- 语法：SELECT *FROM table_name WHERE col_name NOT BETWEEN number1 AND number2
- Features: The query does number1 to number2 data within the range of
- 例子：SELECT *FROM games WHERE GNO NOT BETWEEN 2 AND 9
- Wildcards
例子：SELECT *FROM users WHERE user_name LIKE ‘孙%’
例子：SELECT *FROM users WHERE user_name NOT LIKE ‘孙%’
Null operators query
syntax: SELECT * FROM table_name WHERE col_name IS (NOT) NULL
