MySQL's alter statement usage summary

1: Delete Columns

ALTER table "table name" DROP "column name"

2: Add columns

ALTER table "table name" ADD "column name" INT not NULL COMMENT ' comment description '

3: Modify the column type information

ALTER table "table name" Change "column Name" "New column name (you can use the same name as the original column)" BIGINT not NULL COMMENT ' comment description '

4: Renaming columns

ALTER table "table name" Change "column Name" "New column name" BIGINT not NULL COMMENT ' comment description '

5: Renaming a table

ALTER table "table name" RENAME "Table new name"

6: Delete primary key in table

Alter table "Tables name" Drop PRIMARY key

7: Add primary key

ALTER TABLE sj_resource_charges ADD CONSTRAINT pk_sj_resource_charges PRIMARY KEY (resid,resfromid)

8: Add index

ALTER TABLE sj_resource_charges Add index index_name (NAME);

9: Add a unique limit condition index

ALTER TABLE sj_resource_charges Add unique emp_name2 (cardnumber);

10: Delete Index

ALTER TABLE tablename DROP INDEX emp_name;

MySQL's alter statement usage summary