What is SQL (Structured Query Language) and what are there types...?

       


What is SQL...?

 SQL is a standard language for accessing databases.
 SQL lets you access and manipulates the database.
·         SQL can execute queries against a database.
·         SQL can retrieve data from a database.
·         SQL can insert records in a database.
·         SQL can update records in a database.
·         SQL can delete records from a database.
·         SQL can create a new database.
·         SQL can create new tables in a database.
·         SQL can create stored procedures in a database.
·         SQL can create views in a database.
·         SQL can set permissions on tables, procedures, and views

1. My SQL Data Types                                         
In My SQL there are three main types: text, number, and Date/Time types.

Text types

Data Type
                                                   Description
CHAR(size)
Holds a fixed length string (can contain letters, numbers, and special characters). The fixed size is specified in parenthesis. Can store up to 255 characters                        
VARCHAR(size)
Holds a variable length string (can contain letters, numbers, and special characters).  The maximum size is specified in parenthesis. Can store up to 255 characters. Note: If you put a greater value than 255 it will be converted to a TEXT type.
TINYTEXT
Holds a string with a maximum length of 255 characters.
TEXT
Holds a string with a maximum length of 65,535 characters.
BOLB
For BLOBs (Binary Large Objects). Holds up to 65,535 bytes of data.
MEDIUMTEXT
Holds a string with a maximum length of 16,777,215 characters.
MEDIUMBLOB
For BLOB (Binary Large Objects). Holds up to 16,777,215 bytes of data.
LONGTEXT
Holds a string with a maximum length of 4,294,967,295 characters.
LONGBLOB
For BLOBs (Binary Large Objects).   Holds up to 4,294,967,295 bytes of data.
ENUM(x,y,z,etc.)
Note: The values are sorted in the order you enter them.
You enter the possible values in this format: ENUM(‘X’,’Y’,’Z’).        
SET
Similar to ENUM except that SET may contain up to 64 list items and can store more than one choice.
  
Number Types:

Data type
Description
TYNYINT (size)
-128 to 127 normal. 0 to 225 UNSIGNED*. The maximum number of digits may be specified in parenthesis.
SMALLINT(size)
-32768 to 32767 normal. 0 to 65535 UNSIGNED*. The maximum number of digits may be specified in parenthesis.
MEDIUMIMT(size)
-8388608 to 8388607 normal. 0 to16777215 UNSIGNED*. The maximum number of digits may be specified in parenthesis.
INT(size)
-2147483648 to 2147483647 normal. 0 to 4294967295 UNSIGNED*. The maximum number of digits may be specified in parenthesis.
BIGINT(size)
-9223372036854775808 to 9223372036854775807 normal .0 to 18446744073709551615 UNSIGNED*. The maximum number of digits may be specified in parenthesis.
FLOAT(size,d)
A small number with a floating decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits to the right of the decimal point is specified in the d parameter.
DOUNLE(size,d)
A large number with a floating decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits of the decimal point is specified in the d parameter.
DECIMIAL(size,d)
A DOUBLE stored as a string, allowing for a fixed decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits to the right of the decimal point is specified in the parameter.


*The integer types have an extra option called UNSIGNED.  Normally, the integer goes from  an negative to positive value. Adding the UNSIGNED attribute will move that range up so it starts at zero instead of a negative number.

Data Types

Data types
                                                   Description
DATAE()
A date. Format: YYYY-MM-DD
Note:  The supported range is from ‘1000-01-01’ to ‘9999-12-31’.
DATETIME()
*A date and time combination. Format:  YYYY-MM-DD HH:MI:SS
Note:  The supported range is from is from ‘1000-01-01  00:00:00’ to ‘999-12-31 23:59:59’ 
TIMESTAMP()
*A timestamp. TIMESTAMP values are stored as the number of seconds since the Unix epoch (‘1970-01-01 00:00:00; UTC). Format : YYYY-MM-DD- HH:MI:SS
Note: The supported range is from ‘1970-0-01’ UTC to ‘2038-01-09.
TIME()
A time. Format: HH:MI:SS
Note: The supported range is from ‘-838:59:59
YEAR()
A year in two-digit or four digit format.
Note: Value allowed in four-digit format: 1901 to 2155. Values allowed in two-digit format: 70 to 69, representing years from 1970 to 2069.











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