Stat Nexus - Data Analysis

Machine Learning Timeline. 1940 - 2022

• Data Definition Language (DDL)

CREATE- It is used to create a new table in the database.
Syntax: CREATE TABLE TABLE_NAME (COLUMN_NAME DATATYPES[,....]);

DROP: It is used to delete both the structure and record stored in the table.
Syntax: DROP TABLE;

ALTER: It is used to alter the structure of the database. This change could be either to modify the characteristics of an existing attribute or probably to add a new attribute.
Syntax: ALTER TABLE table_name ADD column_name COLUMN-definition;
ALTER TABLE MODIFY(COLUMN DEFINITION....);

TRUNCATE: It is used to delete all the rows from the table and free the space containing the table.
Syntax: TRUNCATE TABLE table_name;

• Data Manipulation Language (DML)

INSERT: The INSERT statement is a SQL query. It is used to insert data into the row of a table.
Syntax: INSERT INTO TABLE_NAME (col1, col2, col3,.... col N)
VALUES (value1, value2, value3, .... valueN);

UPDATE: This command is used to update or modify the value of a column in the table.
Syntax: UPDATE table_name SET [column_name1= value1,...column_nameN = valueN] [WHERE CONDITION]

DELETE: This command is used to delete components from a table.
Syntax: DELETE FROM table_name WHERE {CONDITION};

• Data Control Language (DCL)

GRANT: It is used to give user access privileges to a database.
Syntax: GRANT SELECT, UPDATE ON MY_TABLE TO SOME_USER, ANOTHER_USER;

REVOKE: It is used to take back permissions from the user.
Syntax: REVOKE SELECT, UPDATE ON MY_TABLE FROM USER1, USER2;

• Transaction Control Language (TCL)

COMMIT: Commit command is used to save all the transactions to the database.
Syntax: COMMIT;

ROLLBACK: Rollback command is used to undo transactions that have not already been saved to the database.
Syntax: ROLLBACK;

SAVEPOINT: It is used to roll the transaction back to a certain point without rolling back the entire transaction.
Syntax: SAVEPOINT SAVEPOINT_NAME;

• Data Query Language (DQL)

SELECT: This is the same as the projection operation of Relational algebra. It is used to select the attribute based on the condition described by WHERE clause.
Syntax: SELECT expressions FROM TABLES WHERE conditions;

https://medium.com/.Abeysinghe/sql-basic-commands-8030e59483fa

SQL Basic Commands • Data Definition Language (DDL)