Structured query language(sql)ppt
- 1. Structured Query Language(SQL) BY., B. Gowarthini C. Divya V. Suruthi
- 2. Agenda: • Introduction • Datatypes of SQL • Operators of SQL • Basic Database Concepts • Processing capabilities of SQL • Joins and its types • Aggregate functions • Stored procedures • Index • Triggers
- 3. Introduction: • SQL is a non procedural language that is used to create, manipulate and process the database. Characteristics of SQL: • Easy to learn and use. • Large volume of DB can be handled easily.
- 4. Datatypes of SQL: • Like programming languages, datatypes are also available in SQL • Most commonly used types: Int Date Long Number varchar/ nvarchar
- 5. Operators of SQL: Operators in SQL: Arithmetic operators : +, -, *, / (Simple mathematical operations) Relational operators : =, <, >, <=, >=, <> (For comparing values) Logical operators : OR, AND, NOT (For condition clause)
- 6. Basic Database concepts: • Data: -Raw facts and figures useful to an organization. -Cannot take decisions on basis of data. • Field : -Set of characters • Record: -Collection of fields • Primary key: -Uniquely identifies the records -Never allow NULL and duplicates • Foreign key: -Referential integrity
- 7. Processing capabilities of SQL • Data Definition Language (DDL) • Views • Data Manipulation Language (DML) • Data Control Language (DCL) • Transaction Control Language (TCL)
- 8. Processing capabilities of SQL Data Definition Language (DDL): Common DDL statements are CREATE, ALTER, DROP. CREATE – To create new DB, table, index, view etc.., ALTER - To alter the table, DB etc.., DROP - To delete objects from DB. View: - View is a kind of virtual table. - It contains rows and columns like a real table. - We can create a view by selecting fields.
- 9. Processing capabilities of SQL Data Manipulation Language (DML): - To manipulate the database objects - Query the DB for information retrieval - Common DML statements are SELECT INSERT DELETE UPDATE
- 10. Processing capabilities of SQL Data Control Language(DCL): - Controlling access to the data - Common DCL commands are GRANT , REVOKE Transaction Control Language (TCL): - Control the transaction in DB system - Common TCL commands are COMMIT, ROLLBACK
- 11. Joins and its types • Used to combine rows from two or more tables, based on a related column between them. Types: - Inner Join - Left Join - Right Join - Full Join - Self Join
- 13. Stored procedures • It stored as an object in the database server. • The code can be reused over and over again and then just call it to execute it. Syntax: CREATE PROCEDURE procedure_name // Create stored proc. AS sql_statement GO; EXEC procedure_name; //Execute a stored procedure
- 14. Index • Used to retrieve data from the DB very fast. • Users cannot see the indexes, they are just used to speed up searches/queries. Syntax: CREATE INDEX index_name ON table_name (column1, column2, ...); Types: Clustered index - rows are stored physically on the disk in the same order Non Clustered index - second list that has pointers to the physical rows.
- 15. Triggers • Special kind of Stored procedure • Automatically invokes whenever a DML and DDL events in DB occurs Syntax: create trigger deep on emp for insert,update,delete as print'you can not insert,update and delete this table i' rollback;