sql data type

7/30/2019 SQL Data Type

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PROJECT

ONSQL DATA TYPE

BY BHARTI . K. SHARMAOF T.Y.B(COM) A

ROLL NO:108



DEFINITION OF DATA

A Data is collection of a logically related

data.Data involves specifying the types of data (

For Example:-Numeric,Alphanumeric,etc),

structures & rules for data to be stored in thedatabase



DATA TYPES IN SQL

Character Data/Text Data (string)

Numeric Data (Integer & real)

Temporal Data (Data & Time)

Boolean Data (True or False)

Missing Data (Null)



CHARACTER DATA/TEXT

DATA(STRING)

Character data can be stored either as fixed-length or variable-length string.

The maximum length for char column is 255 bytes

whereas varchar column is 65,535. As matter of fact,if the strings are having fixed

length then use char(len) otherwise usevarchar(len)

Values in CHAR and VARCHAR columns are sorted& compared in case-insensitive fashion,unless the

BINARY attribute was specified when the tablewas created



NUMERIC DATA (INTEGER & REAL)

Numeric data means numbers and they can

be positive or negative or zero;with decimal

point or without decimal point.If data is

without decimal point then it is integer & if

data is with decimal point then it is (float).



TEMPORAL DATA (DATA & TIME)

Temporal data means Date and/or Time.

If century is not given then century is assumed from 1970

to 2069 i.e.if you give year as 69 then it is taken as 2069

whereas if you give year as 70 then it is taken as 1970.

Type Default Format Storage Required

DATE YYYY-MM-DD 3 Bytes

DATETIME YYYY-MM-DD HH:MI:SS 8 Bytes

TIMESTAMP YYYY-MM-DD HH:MI:SS 4 Bytes

YEAR YYYY 1 Bytes

TIME HHH:MI:SS 3 Bytes



BOOLEAN DATA (TRUE & FALSE)

Boolean data means true or false.Boolean data value of false is zero

or true is nonzero-(generally 1).Storage required is 1 byte.

ENUM

Enum is a list or enumeration of string values.A column of typeENUM can be set to a value from the list.A list can contain

maximum 65,535 different values.This column can contain NULL

(Stored as 1,2,3…).You can prevent NULL values from being

accepted by declaring the column as NOT NULL when creating atable.Values stored in database are integers.



MISSING DATA (NULL)

In some cases it is not possible or applicable to

provide a value for a particular column in your

table.In this case thr column is said to be

NULL,which means absence of value.NULL is usedfor various cases where a value cannot be supplied

such as Not Applicable or Unknown or Empty Set



NAME :PINKY YADAV

T.Y.BCOM (A)



PRIMARY KEY

A table typically has a column or

combination of columns that contain values

that uniquely identify each row in the table.

This column, or columns, is called theprimary key (PK) of the table and enforces

the entity integrity of the table. Because

primary key constraints guarantee uniquedata, they are frequently defined on an

identity column.



When you specify a primary key constraint for atable, the Database Engine enforces datauniqueness by automatically creating a unique

index for the primary key columns. This indexalso permits fast access to data when theprimary key is used in queries. If a primary keyconstraint is defined on more than one column,

values may be duplicated within one column,but each combination of values from all thecolumns in the primary key constraint definitionmust be unique.



AS SHOWN IN THE FOLLOWINGILLUSTRATION, THE PRODUCT AND

VENDORID COLUMNS IN THEPURCHASING.PRODUCTVENDORTABLE FORM A COMPOSITE PRIMARYKEY CONSTRAINT FOR THIS TABLE.THIS MAKES SURE THAT THAT EVERYROW IN THE PRODUCTVENDOR TABLE

HAS A UNIQUE COMBINATION OFPRODUCTID AND VENDORID. THIS



FOREIGN KEY



THANK YOU

sql data type

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