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Hi,
To create a query on a database I am getting confused between some SQL commands. They are DDL, DML or DCL commands. I have a database which is needed to link with a small table. For that I had tried to create everything but for passing on the commands errors pops out. How can I differentiate between this three languages of SQL. Thank in advance.
The SQL is divided into various languages to be the defining elements of a database or data handling or management of access rights to data and transactions or data mining. It is a declarative language like that is to say that you specify the properties of data that you want without manipulating logically implement procedures that allow physical manipulation.
Language data description (DDL Data Definition Language). It contains three commands that allow the administration of a database, these commands are: First CREATE used to Create tables or indexes. Then ALTER used for Changing tables or indexes and the DROP which is used to Remove table or index. The generator included tools in our workshop Oracle Designer allows us to generate scripts for multiple products or versions. The code for creating database can only be issued either as scripts or either be executed directly on the targeted database.
DML stands for Data Manipulation Language. It is the Language of ata manipulation which includes three commands for the latest data from a table, these commands. They are Insert which is used to add new rows into a table. The second one is update which updates some fields in a row in a table and Delete to removing unnecessary rows in a table.
DCL commands are Data Control Language. The different commands which come under this is Grant for assigning access rights, Revoke to remove access rights, Commit for taking account of recent transactions for updated data and Rollback for removal of recent transactions and restore the old data. The code for creating database may be issued in the form of scripts or run directly on the targeted database. These options DDL Files Only, or ODBC Database above. In all cases, scripts will be created and registered by setting attributes Prefix File and Directory.
Query language data (for DQL Data Query Language). Although consisting of only one SELECT statement, the latter being the most used because if the population of a database is an important step, the various requests for data extraction are important steps for all type of use. The command for it is SELECT which Extracts data are projected by selection with restrictions or by grouping.