1 / 27

SQL

SQL . SQL Server : Overview SQL : Overview Types of SQL Database : Creation Tables : Creation & Manipulation Data : Creation & Manipulation Data : Retrieving using SQL. SQL : Overview. Is the standard command set used to communicate with the relational database management systems

debra-mcintosh
Download Presentation

SQL

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. SQL • SQL Server : Overview • SQL : Overview • Types of SQL • Database : Creation • Tables : Creation & Manipulation • Data : Creation & Manipulation • Data : Retrieving using SQL

  2. SQL : Overview • Is the standard command set used to communicate with the relational database management systems • Can do Creating databases, Creating tables, Querying and Manipulating data and granting access to the users • English like structure • is by nature flexible

  3. Types of SQL Commands • SQL statements are divided into the following categories • Data Definition Language (DDL) • Data Manipulation Language (DML) • Data Query Language (DQL) • Data Control Language (DCL) • Data Administration Statements (DAS) • Transaction Control Statements (TCS)

  4. Data Definition Language • Is used to create, alter and delete database objects • The commands used are • CREATE • ALTER • DROP

  5. Data Manipulation Language • Used to insert data into the database, modify and delete the data in the database • Three DML statements • INSERT • UPDATE • DELETE

  6. Data Query Language • This statement enables you to query one or more tables to get the information • commonly used SQL statements • SQL has only one data query statement • SELECT

  7. Data Control Language • The DCL consists of commands that control the user’s access to the database objects • The DCL is mainly related to the security issues • The DCL commands are • GRANT - Giving access to the data • REVOKE - Denying access to the data

  8. Data Administration Statements • DASs allow the user to perform audits and analysis on operations within the database. • Used to analyze the performance of the system • Data Administration commands are • START AUDIT • STOP AUDIT

  9. Transaction Control Statements • TCSs are statements, which manage all the changes made by the DML statements • Some of the TCSs are • COMMIT • ROLLBACK • SAVEPOINT • SET TRANSACTION

  10. Databases • Collection of related data and manipulation of that data • Can create database using SQL command • CREATE DATABASE databasename

  11. Tables • Are the basic building blocks in any RDBMS • contains rows and columns of data • using DDL commands, we can create , alter and delete tables • Creation of table includes the properties of the columns

  12. Create statement CREATE TABLE table-name (column-1-definition [,column-2-definition] ….. [,column-n-definition] [,primary key (column name)] [.alternate key (column name)] [,Foreign key (column name) ]);

  13. Column definition • columnName data-type [NULL | NOT NULL [WITH DEFAULT | UNIQUE]] • NULL - RDBMS insert a null in that column if the user does not specify a value • NOT NULL - column should have a value • WITH DEFAULT - the RDBMS will substitute the default values • UNIQUE - no duplicate values will be allowed

  14. Data types • char(n) - represents a fixed length of string of ‘n’ characters where n>0 and is an integer • varchar(n) - varying length string whose max length is ‘n’ • bit(n) - represents a fixed length string of exactly ‘n’ bits • decimal(p, q) - represents a decimal number, ‘p’ digits and with decimal point ‘q’ digits from right

  15. Data Types • float(n) - represents the floating point number • int - represents a signed integer • datetime - represents the date/time • money - represents the currency

  16. 2nd form of CREATE • CREATE TABLE new-table-name LIKE table-name • when a table is created from an existing table only the structure is copied; the primary, alternate and foreign key definitions is not inherited

  17. Modifying a Table • An existing table can be modified by using the ALTER TABLE statement • ALTER TABLE table-name ADD column definition • ALTER TABLE table-name Add CONSTRAINT constraint name Primary key (column name)

  18. Deleting a table • An existing table can be deleted at any time by using the DROP TABLE statement • DROP TABLE table-name • specified table is deleted from the system • all the data for that table also will be deleted

  19. Inserting rows into a table • INSERT INTO table-name [[column [,column]….]] values [literal[,literal]…]]; • a single row is inserted into the table, having specified columns • INSERT INTO table-name [[column [,column]….]] subquery; • the subquery is evaluated first and a copy of the result(usually multiple rows) is inserted into the table

  20. Updating fields in a row • UPDATE table-name SET column-name = expr [WHERE condition] • table-name : table for the data to be updated • SET clause : the set of new values to be set • WHERE clause : condition will be checked and particular record gets updated

  21. Deleting of data from the table • DELETE FROM table-name WHERE condition • Depending on the condition the record will be deleted from the table

  22. SELECT statements • SELECT - A keyword that tells the database this command is a query. All queries begin with this word followed by a space • the select command simply instructs the database to retrieve information from a table

  23. Different features applied to a simple statement • All columns • Qualified Retrieval • Eliminating Duplicates • Using Boolean(IN, BETWEEN, LIKE) • Using Escape clause • Computed values • Involving nulls

  24. All Columns • SELECT * FROM Table-name • Qualified Retrieval • SELECT * FROM table-name WHERE condition • can use all comparision operators (=, <>, <, >, <=, >=) in the WHERE clause • can contain multiple comparison with AND, OR, NOT • Eliminating Duplicates • SELECT DISTINCT column-name FROM table-name

  25. Using Boolean Operators • IN • SELECT * FROM table-name WHERE column-name IN (val1, val2, val3…); • BETWEEN • SELECT * FROM table-name WHERE column-name BETWEEN val1 and val2 • between is an inclusive operator • values matching either of the boundary values cause the predicate to be true

  26. NOT BETWEEN • SELECT * FROM table-name WHERE column-name NOT BETWEEN val1 and val2 • LIKE • SELECT * FROM table-name WHERE column-name LIKE ‘string%’ • LIKE ‘_%’ • Escape Sequence • SELECT * FROM table-name WHERE column-name LIKE ‘%\_%’

  27. Computed Values • SELECT column1, column2Expression FROM table-name WHERE condition • NULLS • SELECT * FROM table-name WHERE column-name IS NULL • ORDER BY • SELECT * FROM table-name ORDER BY column-name DESC

More Related