Lecture 9 (Week 8) - Structured Query Language (SQL).pptx
- 1. “Database Management Systems” CS-222 Lecture 17 “Structured Query Language (SQL)” Dr. Muhammad Muneer Umar By: Lecturer in Computer Science Institute of Computing KUST, Pakistan
- 2. Objective of the today’s topic • To know the fundamentals about Structure Query Language (SQL) • To know the importance and usability of SQL in RDBMS • To understand the basic syntax of SQL code • To define SQL statements, clauses and keywords • To learn about the utilization and management of RDBMS through SQL • To understand the categories of SQL statements
- 3. CONTENTS • Introduction • What can SQL do with databases? • SQL Query • SQL statements, clauses and keywords • Rules for typing SQL statements • SQL commands • DDL: Data Definition Language • DML: Data Manipulation Language • TCL: Transaction Control Language • DCL: Data Control Language • DQL: Data Query Language
- 4. INTRODUCTION • “Structure Query Language(SQL) is a database query language used for storing and managing data in Relational DBMS”. • First commercial language introduced for E.F Codd's Relational model of database. • Standardization: • American National Standards Institute (ANSI) in 1986, • International Organization for Standardization (ISO) in 1987 • Used by almost all RDBMS(MySql, Oracle, Infomix, Sybase, MS Access)
- 5. RELATIONS IN SQL PName Price Category Manufacturer Gizmo $19.99 Gadgets GizmoWorks Powergizmo $29.99 Gadgets GizmoWorks SingleTouch $149.99 Photography Canon MultiTouch $203.99 Household Hitachi Product Attribute names Table name Tuples or rows
- 6. What can SQL do with databases? Execute queries against a database Retrieve data from a database Insert records in a database Update records in a database Delete records from a database Create new databases Create new tables in a database Create stored procedures in a database Create views in a database Set permissions on tables, procedures, and views
- 7. SQL QUERY BASIC FORM: SELECT <attributes> FROM <one or more relations> WHERE <conditions> SAMPLES: SELECT reg, sname FROM student_table WHERE city = ‘Kohat’ ; INSERT INTO student_table (reg, sname, city) VALUES (‘CS123456’ , ‘Farhan’ , ‘Kohat’ ); DROP TABLE student_table ; SHOW TABLES ;
- 8. SQL STATEMENTS, CLAUSES AND KEYWORDS SELECT std_id, std_name, std_age FROM student ORDER BY std_id; 1) KEYWORD The individual tokens (elements) which are predefined, and we cannot change their meaning are known as SQL keyword. In the given example: The keyword are "SELECT" , "FROM“ and “ORDER BY” 2) CLAUSE Clause is a part of an SQL statement. In the given example: The clause are "SELECT std_id, std_name, std_age“ and “ORDER BY std_id” 3) STATEMENT A complete query may refer to as a "statement" and we can say that set of two or more clause are known as a "statement" in SQL.
- 9. RULES FOR TYPING SQL STATEMENTS • SQL statement is not case sensitive you may write the statement in any case (even keywords like SELECT, FROM, DROP etc.) are not case sensitive. • You can write a complete SQL statement in a single line (but, you should separate them in multiple lines, each clause should be written in separate line). • You may use to enhance the SQL Query readability. Note: keywords should be written in UPPERCASE (for better readability) and other words should be written in lowercase.
- 10. RULES FOR TYPING SQL STATEMENTS • SAME: • SELECT Select select • Product product • CONSTANTS/VALUES: • Correct ‘abc’ • Wrong “abc” • Use single quote (‘) for strings/character values • ‘Ahmed Khan’ , ‘Peshawar’ , ‘+92-3331234567 • Use grave accent (`) for object names • `table_name` , `std_info_view` , `procedure1` DIFFERENT: ‘Ali’ ‘ali’
- 11. SQL COMMANDS • SQL defines following ways to manipulate data stored in an RDBMS. • DDL: Data Definition Language • DML: Data Manipulation Language • TCL: Transaction Control Language • DCL: Data Control Language • DQL: Data Query Language
- 12. DDL: Data Definition Language • This includes changes to the structure of the table • like creation of table, altering table, deleting a table etc. • All DDL commands are auto-committed. • That means it saves all the changes permanently in the database Command Description CREATE to create new table or database ALTER for alteration TRUNCATE delete data from table DROP to drop a table RENAME to rename a table
- 13. DML: Data Manipulation Language • DML commands are used for manipulating the data stored in the table and not the table itself. • DML commands are not auto-committed. • It means changes are not permanent to database, they can be rolled back. Command Description INSERT to insert a new row UPDATE to update existing row DELETE to delete a row MERGE merging two rows or two tables
- 14. TCL: Transaction Control Language • These commands are to keep a check on other commands and their affect on the database. • It can also make any temporary change permanent. Command Description COMMIT to permanently save ROLLBACK to undo change SAVEPOINT to save temporarily
- 15. DCL: Data Control Language • Data control language are the commands to grant and take back authority from any database user. Command Description GRANT grant permission of right REVOKE take back permission.
- 16. DQL: Data Query Language • Data query language is used to fetch data from tables based on conditions that we can easily apply Command Description SELECT retrieve records from one or more table
- 17. SUMMARY • SQL: A language used for management of RDBMS • SQL can be used to perform various operations on RDBMS • Also we can do managerial task with SQL • SQL is not case sensitive. • SQL commands can be classified as: • DDL, DML, TCL, DCL, DQL
- 18. THANKS
- 19. Sample Queries (Practice in Workbench): • Select a database • Select Data from Database Table • Insert Data into a table • Update existing data • Delete data from a table • Create a new table