SQL Basic Grooming

I. Basic usage

Inquire:

SELECT * FROM table name (where column name = ' &ABC ');

eg.

SELECT * from EMP;

Increase:

When inserting multiple values, use values:

Insert into table name values (value 1, value 2, ...);

Insert into table name (column 1, column 2, ...) VALUES (value 1, value 2, ...);

eg.

Insert into table (name) VALUES (' abc ');

When inserting null values, use value:

eg.

Insert into table value (NULL);

By deleting:

Delete from table name where condition;

Note: 1. Delete the data only, do not delete the table itself, to delete the entire table, use the drop table;2.where conditional clause, if none, will delete all the data in the table.

Change:

Update table name set column name = expression where condition;

eg. put the students table, the YM of this person's gender into female

Update students set sex= ' female ' where name= "ym";

Two. SQL statement Classification

DML Statements ( Data manipulation Statements ) [INSERT, UPDATE, delete]

DDL Statements ( data definition Language ) [CREATE table drop table ...]

DQL Statement ( data query Statement ) [select]

DTL Statement ( Data Control Language ) commit rollback

SQL Basic Grooming