In this article, you will learn the SQL command categories and their sub-categories. SQL is an open-source data management system. The SQL query is used to retrieve and manipulate the data from the table. With the help of SQL command we can query, filter, sort, join, group and modify the data in the database. Show SQL commands are categorized into below 5 categories:
DDL (Data Definition Language)DDL or Data definition language is actually the definition or description of the database structure or schema, it won't change the data inside the database. Create, modify, and delete the database structures, but not the data. Only These commands are not done by all the users, who have access to the database via an application. CREATE Create the database or its object (ie table, index, view, function etc.). Syntax CREATE DATABASE databasename Example
Syntax CREATE TABLE table_name ( Example
DROP Drop command helps to delete the object from the database (ie table, index, view, function, etc.). Syntax DROP object object_name Example
Syntax DROP DATABASE database_name Example
ALTER Alter command is helpful to change or modify the structure of the database or its object. Syntax ALTER TABLE table_name Example
Syntax ALTER TABLE table_name Example
1) SQL Server / MS Access Syntax ALTER TABLE table_name Example
2) My SQL / Oracle (prior version 10G) Syntax ALTER TABLE table_name Example
3) Oracle 10G and later Syntax ALTER TABLE table_name Example
TRUNCATE Truncate command helps to remove all records from a table. Syntax TRUNCATE TABLE table_name Example
COMMENT Comment is helpful to add comments to the data dictionary."--" is used to comment the notes. Syntax --(notes,examples) Example 0RENAME Rename is helpful to rename an object existing in the database. 1) PostgreSQL Syntax ALTER DATABASE "Old_DatabaseName" RENAME TO "New_DatabaseName"; Example 12) MySQL Example SQL Command for Dump copy 2SQL Command for creating new DB 3SQL Command for Import 4Also for Unix, database names are case-sensitive 3) SQL Server In SQL Server we can rename the database through server application, by right click the existing database and renaming it. DQL (Data Query Language)DQL or data query language is to perform the query on the data inside the schema or object (ie table, index, view, function, etc). With the help of DQL query we can get the data from the database to perform actions or operations like analysing the data. SELECT Select query on a table or tables to view the temporary table output from the database. Syntax Select * from Table_Name; Example 5DML(Data Manipulation Language)DML or Data Manipulation Language is to manipulate the data inside the database. With the help of DML commands, we can insert, delete, change the data inside the database. INSERT Insert command is helpful to insert the data into a table. 1) All the column names are mentioned in the insert statement. Syntax INSERT INTO table_name (column1, column2, column3, ...) Example 62) Column names do not need to mentioned in the query, Values should be given in the order according to the column. Syntax INSERT INTO table_name Example 7UPDATE Update command is helpful to update the existing data in a table. Syntax UPDATE table_name Example 8DELETE Delete command helps to delete the records from a database table. Syntax DELETE FROM table_name WHERE condition; Example 9LOCK Lock command is helpful to lock the table to control concurrency. Syntax LOCK TABLE table-Name IN { SHARE | EXCLUSIVE } MODE Example 0CALL Call command is helping to Call a PL/SQL or JAVA subprogram. Syntax EXEC SQL EXPLAIN PLAN It describes the access path to the data. Syntax EXPLAIN PLAN FOR Example 1This query explanation will be stored in the PLAN_TABLE table. We can then select the execution plan to review the queries. DCL (Data Control Language)DCL or Data Control Language is to provide rights, permissions, and other controls of the database system. GRANT GRANT command is helpful to provide privileges to the database. Syntax GRANT privileges_names ON object TO user Example 2Syntax GRANT EXECUTE ON [ PROCEDURE | FUNCTION ] object TO user REVOKE Revoke command is to withdraw the user’s access privileges given by using the GRANT command. Syntax REVOKE privileges ON object FROM user Example 3Syntax REVOKE EXECUTE ON [ PROCEDURE | FUNCTION ] object FROM user TCL (Transaction Control Language)TCL or Transaction Control Language happens to a transaction in the database. COMMIT Commit command is to commit Transaction after insert or delete in the database. Syntax Commit; Example 4ROLLBACK Rollback command is to rollback a transaction in case of any error occurs. Syntax Rollback; Example 5SAVEPOINT Savepoint command is to Set a savepoint within a transaction. If transaction happens in big data, then for checking and rollup can't do it with all the data, to rollback the small part of the data we use savepoint query. Syntax SAVEPOINT savepoint_name SET TRANSACTION Set command is to Specify the characteristics of the transaction. Syntax SET TRANSACTION Access NAME transaction_name SummaryIn this article, you have learned about the various SQL commands and simple SQL queries with examples. What are DDL DML and DCL commands in SQL?Within SQL are three main sub-languages that are used to manipulate and manage both the database and data itself: DCL, DDL, and DML. DCL stands for data control language. DDL stands for data definition language. DML stands for data manipulation language. Each sub-language has slightly different purposes and commands.
What are DML commands in SQL?DML is an abbreviation of Data Manipulation Language. The DML commands in Structured Query Language change the data present in the SQL database.. SELECT Command.. INSERT Command.. UPDATE Command.. DELETE Command.. What are the 5 types of SQL commands?There are five types of SQL commands: DDL, DML, DCL, TCL, and DQL.
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