Database Statement Learning

1. Query statements

　(1) Select column name, column name, ...

From table name: Setect * FROM table name get all contents in table

(2) Select DISTINCT column name, column name, ...

From table name//Get a different value for a column

(3) Select column name

From table name

Where column operator value//value if text format, use ' ', operator not equal to <>

And and or are used in the where statement to assemble multiple conditions.

Order BY Column name DESC/ASC//Sort result set DESC is descending, ASC is ascending

2. Inserting data into the table

(1) INSERT INTO form

Values (value 1, value 2, ...); You need to assign a value to each column in the table

(2) Insert into table (column name, column name, ...) ）

Values (value 1, value 2, ...) You need to assign a value to an enumerated column name item

It is important to note that the key value must be unique

3. Modify the Tabular Data

Update table name

Set Column name = new value//corresponding column value

where column name = value//corresponding row

4. Delete rows from a table

Delete from table name

where Column name = value

Delete all rows Delete * FROM table name or delete from table name

5. Like operator and wildcard character

Where column name is like '//single quotation mark if you do not know the whole content can use a wildcard character

% can replace one or more characters, but be aware of where the% is placed

_ Can replace one character

[string] Any single byte in the string, and be aware of where it is placed

[! string] [^ string] non-string any one character//back two less