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Articles Reviews Structured Query Language
Written by Adi Bach   
Friday, 05 October 2007

Every relational database is built of tables, which consist of various columns. Each column is designed to contain a special, predefined piece of data. Depending on the kind of data you want to store, an appropriate data type must be chosen. A column based on a certain data type can only store information fitting the demands of the data type of the column. For example, a column that has been defined as integer value must not be used to store text.

PostgreSQL provides a powerful set of data types, which can be retrieved by using the \dT command in psql:



phpbook=# \dT                                       List of data types
            Name             |                            Description
-----------------------------+-------------------------------------------------
------------------
 abstime                         | absolute, limited-range date and time (Unix system time)
 aclitem                          | access control list
 bigint                            | ~18 digit integer, 8-byte storage
 bit                                | fixed-length bit string
 bit varying                      | variable-length bit string
 boolean                         | boolean, 'true'/'false'
 box                               | geometric box '(lower left,upper right)'
 bytea                            | variable-length string, binary values escaped
 "char"                            | single character
 character                       | char(length), blank-padded string, fixed storage length
 character varying             | varchar(length), non-blank-padded string,variable storage length
 cid                                 | command identifier type, sequence in transaction id
 cidr                                | network IP address/netmask, network address
 circle                              | geometric circle '(center,radius)'
 date                                | ANSI SQL date
 double precision                | double-precision floating point number, 8-byte torage
 inet                               | IP address/netmask, host address, netmask optional
 int2vector                       | array of 16 int2 integers, used in system tables
 integer                            | -2 billion to 2 billion integer, 4-byte storage
 interval                            | @ <number> <units>, time interval
 line                                | geometric line '(pt1,pt2)'
 lseg                               | geometric line segment '(pt1,pt2)'
 macaddr                         | XX:XX:XX:XX:XX:XX, MAC address
 money                           | $d,ddd.cc, money
 name                             | 31-character type for storing system identifiers
 numeric                         | numeric(precision, decimal), arbitrary precision number
 oid                                 | object identifier(oid), maximum 4 billion
 oidvector                        | array of 16 oids, used in system tables
 path                               | geometric path '(pt1,...)'
 point                              | geometric point '(x, y)'
 polygon                          | geometric polygon '(pt1,...)'
 real                                | single-precision floating point number, 4-byte storage
 refcursor                         | reference cursor (portal name)
 regproc                           | registered procedure
 reltime                            | relative, limited-range time interval (Unixdelta time)
 "SET"                             | set of tuples
 smallint                            | -32 thousand to 32 thousand, 2-byte storage
 smgr                               | storage manager
 text                                | variable-length string, no limit specified
 tid                                  | (Block, offset), physical location of tuple
 timestamp withouttime zone  | date and time
 timestamp with time zone      | date and time with time zone
 time without time zone         | hh:mm:ss, ANSI SQL time
 time with time zone               | hh:mm:ss, ANSI SQL time
 tinterval                               | (abstime,abstime), time interval unknown                     |
 xid                                      | transaction id
(47 rows)


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Last Updated ( Saturday, 20 September 2008 )
 
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