ComE 223 (Slide 2).pdf

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SQL

Structure Query Language

7/23/2019 ComE 223 (Slide 2).pdf


is mainly classified into Data Definition

Language (DDL) and Data Manipulation

Language (DML).

ANSI: “The standard language for relational database management systems”

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• Common RDBMS that uses SQL

– Oracle

– Sybase – Microsoft SQL Server

– Access

–Ingres

– MySQL

Although they

used SQL, they

have their own

proprietary

extensions that

are only used

w/in their

systems

But common are

the standard SQL

Commands

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Using SQL as a DDL (data definition

language)

• means creating a database, creating tables and adding them to a

database, updating the design of existing tables, and removing

tables from a database.

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Database tables• A RDBMS contains : one or more objects

tables (data or information is stored)

Course Code Course Description Units Co-Requisite

ComE 223 Advance Programming 3 ComE 223L

Chem 4 Chemistry 3 Chem4L

EM 111 Algebra 5 none

Are uniquely identified by

their names.

Comprises of rows And columns

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CREATE DATABASE

• Statement can be used to create a database

• Syntax: CREATE DATABASE <databaseName>

Example:

The ff. statement created a database named myDB

Create Database myDB

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CREATE TABLE• statement creates a table and adds it to the database

• Syntax:

CREATE TABLE <tableName> (colDefinition,…, colDefinition)

– Each columnDefinition is of the form ColumnName columnType

• Common Data types:

– Char(n) - An n character text string

– Integer - An integer value

– Float - A floating point value

– Bit - A boolean (1 or 0) value

– Date - A date value

–

Time - A time value

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Example of create table

CREATE TABLE Friends(

name char(100),

address char(50),bday date

)

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ALTER TABLE (mysql syntax)

• Rename column

• Add column

•

Change column location• Delete column

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The DROP TABLE Statement

• DROP TABLE tableName

– deletes a table permanently from the database

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Using SQL as a Data Manipulation

Language

• One of SQL Primary use

– Update data

• inserting new rows into a database,

• deleting rows from a database, and

• modifying/updating existing rows.

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INSERT

• INSERT INTO tableName VALUES ('values 1 ' ,…, 'valuen' )

• Values should be surrounded by single quotes.

• Add a complete row

• Alternative or Add a partial row

– INSERT INTO tableName(columnName1,….,columnNamem) VALUE

('value1',…,'valuem')

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Delete

• deletes a row from a table

• DELETE FROM tableName [WHERE condition]

•

All rows of the table that meet the conditionof the WHERE clause are deleted from the

table.

• If the WHERE clause is omitted, all rows of the

table are deleted

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Update

• used to update an existing row of a table

• UPDATE tableName SET columnName1 ='value1", …...,columnName = 'value' [WHERE

condition]• All the rows of the table that satisfy the

condition of the WHERE clause are updated by

setting the value of the specified values.• If the WHERE clause is omitted, all rows of the

table are updated.

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Using SQL as a Data Query Language

• retrieving data contained in a database

• SELECT columnList1 FROM table1 ,…, tablem [WHEREcondition]

• Select/retrieve data for – Comparison

– Range

– Set membership

– Pattern matching

– Null value test

– Compound search condition

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Relational and Logical Comparisons

• Comparison Test- used to compare equal to, not equal to, less

than, less than or equal to, greater than, greater than or equal

– Use of relational operators

– =, <>,<,<=,>=,>

• Range Test- test whether the value lies within the range or not

– Between and not between

• Set membership test-test whether the value is present in the

list of values

– IN, NOT IN

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• Pattern Matching Test- test is employed to find a string

starting with a character/or several characters

– LIKE (%, _ )

– E.G: WHERE NAME LIKE ‘A%BC_’

• NULL VALUE TEST-test whether the column contains null value.

– IS NULL

• COMPOUND SEARCH CONDITON- test for more than

one condition

– AND/OR/NOT is used

• ORDER BY-retrieve data in some order

– asc,desc

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• Union-is used to combine two or more tables

• Criteria

– The tables must contain same number of columns.

– Data type of each should match that of the other

– Neither can be stored but combined can be

stored.

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Functions

• used to act upon single column or

multicolumn for a specified job.

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Assignment (1 whole yellow paper)

• Describe, explain, and give example of the ff.concepts. Handwritten, write legibly. – Alias table

– Distinct

– Union

– Join (Equi join, non equi join, outer join)

– Query on queries

– Rules for Multi Table Query Processing

• Essay1. How SQL can be used as a Data Query Language?

2. How SQL can be used for Data Manipulation?

Documents

ComE 223 (Slide 2).pdf