[Query Statement]--mysql query statement Knowledge points Summary

1. Query fields
#查询所有字段
#查询指定字段

2. Querying a specified record (where condition expression)
#比较
#指定范围
#指定集合
#匹配字符
#查询空值
#带IN关键字的集合查询
range Query #带BETWEEN and keyword
#带LIKE的字符匹配查询
#带AND | Multi-criteria query for or

3. Further operation of the query results
#distinct查询结果不重复
sort #order by Query results
#limit限制查询结果数目与指定初始位置
#union合并查询结果

4. Aggregate Functions
#count ()
#sum ()
#avg ()
#max ()
#min ()

5. Packet Query (group BY)
#group by + group_concat ()
#group by + aggregate function
#group by + have
#group by + with rollup

6. Connection Query
#内连接查询
#外连接查询
|--> left connection query
|--> Right Connection query
#复合条件的连接查询

7. Sub-query
#带IN的子查询
#带比较运算符的子查询
#带exists的子查询
#带any的子查询
#带all的子查询

8. Alias tables and Fields

9. Using Regular expression Queries
#查询以特定字符 (String) record at the beginning
record at the end of a #查询以特定字符 (string)
#使用 "." or "*" or "+" to match 1 or more characters
#匹配指定字符 (String)
#{m,n} match string consecutive occurrences

[Query Statement]--mysql query statement Knowledge points Summary