12.19 DESCRIBE
Syntax
DESC[RIBE] {[schema.]object[@db_link]}Lists the column definitions for the specified table, view or synonym, or the specifications for the specified function or procedure.
Terms
schemaRepresents the schema where the object or permission to describe the object resides. If you omit schema and the object is not a public synonym, SQL*Plus assumes you own object.
objectRepresents the table, view, type, procedure, function, package or synonym you wish to describe.
@db_linkConsists of the database link name corresponding to the database where object exists. For more information on which privileges allow access to another table in a different schema, refer to the Oracle Database SQL Language Reference.
Usage
The description for tables, views, types and synonyms contains the following information:
-
each column's name
-
whether or not null values are allowed (NULL or NOT NULL) for each column
-
datatype of columns, for example, CHAR, DATE, LONG, LONGRAW, NUMBER, RAW, ROWID, VARCHAR2 (VARCHAR), or XMLType
-
precision of columns (and scale, if any, for a numeric column)
When you do a DESCRIBE, VARCHAR columns are returned with a type of VARCHAR2.
The DESCRIBE command enables you to describe objects recursively to the depth level set in the SET DESCRIBE command. You can also display the line number and indentation of the attribute or column name when an object contains multiple object types. For more information, see the SET command.
To control the width of the data displayed, use the SET LINESIZE command.
Columns output for the DESCRIBE command are typically allocated a proportion of the linesize currently specified. Decreasing or increasing the linesize with the SET LINESIZE command usually makes each column proportionally smaller or larger. This may give unexpected text wrapping in your display. For more information, see the SET command.
The description for functions and procedures contains the following information:
-
the type of PL/SQL object (function or procedure)
-
the name of the function or procedure
-
the type of value returned (for functions)
-
the argument names, types, whether input or output, and default values, if any
-
the ENCRYPT keyword to indicate whether or not data in a column is encrypted
Examples
To describe the view EMP_DETAILS_VIEW, enter
DESCRIBE EMP_DETAILS_VIEW
Name Null? Type
----------------------------------------- -------- ----------------
EMPLOYEE_ID NOT NULL NUMBER(6)
JOB_ID NOT NULL VARCHAR2(10)
MANAGER_ID NUMBER(6)
DEPARTMENT_ID NUMBER(4)
LOCATION_ID NUMBER(4)
COUNTRY_ID CHAR(2)
FIRST_NAME VARCHAR2(20)
LAST_NAME NOT NULL VARCHAR2(25)
SALARY NUMBER(8,2)
COMMISSION_PCT NUMBER(2,2)
DEPARTMENT_NAME NOT NULL VARCHAR2(30)
JOB_TITLE NOT NULL VARCHAR2(35)
CITY NOT NULL VARCHAR2(30)
STATE_PROVINCE VARCHAR2(25)
COUNTRY_NAME VARCHAR2(40)
REGION_NAME VARCHAR2(25)To describe a procedure called CUSTOMER_LOOKUP, enter
DESCRIBE customer_lookup
PROCEDURE customer_lookup
Argument Name Type In/Out Default?
---------------------- -------- -------- ---------
CUST_ID NUMBER IN
CUST_NAME VARCHAR2 OUTTo create and describe the package APACK that contains the procedures aproc and bproc, enter
CREATE PACKAGE apack AS PROCEDURE aproc(P1 CHAR, P2 NUMBER); PROCEDURE bproc(P1 CHAR, P2 NUMBER); END apack; /
Package created.DESCRIBE apack
PROCEDURE APROC
Argument Name Type In/Out Default?
------------------------------ ----------------------- ------ --------
P1 CHAR IN
P2 NUMBER IN
PROCEDURE BPROC
Argument Name Type In/Out Default?
------------------------------ ----------------------- ------ --------
P1 CHAR IN
P2 NUMBER INTo create and describe the object type ADDRESS that contains the attributes STREET and CITY, enter
CREATE TYPE ADDRESS AS OBJECT
( STREET VARCHAR2(20),
CITY VARCHAR2(20)
);
/Type created.DESCRIBE address
Name Null? Type
----------------------------------------- -------- ----------------------
STREET VARCHAR2(20)
CITY VARCHAR2(20)To create and describe the object type EMPLOYEE that contains the attributes LAST_NAME, EMPADDR, JOB_ID and SALARY, enter
CREATE TYPE EMPLOYEE AS OBJECT (LAST_NAME VARCHAR2(30), EMPADDR ADDRESS, JOB_ID VARCHAR2(20), SALARY NUMBER(7,2) ); /
Type created.DESCRIBE employee
Name Null? Type
----------------------------------------- -------- ----------------------
LAST_NAME VARCHAR2(30)
EMPADDR ADDRESS
JOB_ID VARCHAR2(20)
SALARY NUMBER(7,2)To create and describe the object type addr_type as a table of the object type ADDRESS, enter
CREATE TYPE addr_type IS TABLE OF ADDRESS; /
Type created.DESCRIBE addr_type
addr_type TABLE OF ADDRESS
Name Null? Type
----------------------------------------- -------- ----------------------
STREET VARCHAR2(20)
CITY VARCHAR2(20)To create and describe the object type addr_varray as a varray of the object type ADDRESS, enter
CREATE TYPE addr_varray AS VARRAY(10) OF ADDRESS; /
Type created.DESCRIBE addr_varray
addr_varray VARRAY(10) OF ADDRESS
Name Null? Type
----------------------------------------- -------- ----------------------
STREET VARCHAR2(20)
CITY VARCHAR2(20)To create and describe the table department that contains the columns DEPARTMENT_ID, PERSON and LOC, enter
CREATE TABLE department (DEPARTMENT_ID NUMBER, PERSON EMPLOYEE, LOC NUMBER ); /
Table created.DESCRIBE department
Name Null? Type
----------------------------------------- -------- ----------------------
DEPARTMENT_ID NUMBER
PERSON EMPLOYEE
LOC NUMBERTo create and describe the object type rational that contains the attributes NUMERATOR and DENOMINATOR, and the METHOD rational_order, enter
CREATE OR REPLACE TYPE rational AS OBJECT (NUMERATOR NUMBER, DENOMINATOR NUMBER, MAP MEMBER FUNCTION rational_order - RETURN DOUBLE PRECISION, PRAGMA RESTRICT_REFERENCES (rational_order, RNDS, WNDS, RNPS, WNPS) ); /
CREATE OR REPLACE TYPE BODY rational AS OBJECT MAP MEMBER FUNCTION rational_order - RETURN DOUBLE PRECISION IS BEGIN RETURN NUMERATOR/DENOMINATOR; END; END; / DESCRIBE rational
Name Null? Type
------------------------------ -------- ------------
NUMERATOR NUMBER
DENOMINATOR NUMBER
METHOD
------
MAP MEMBER FUNCTION RATIONAL_ORDER RETURNS NUMBERTo create a table which contains a column of XMLType, and describe it, enter
CREATE TABLE PROPERTY (Price NUMBER, Description SYS.XMLTYPE);
Table createdDESCRIBE PROPERTY;
Name Null? Type
----------------------------------------- -------- ----------------------
PRICE NUMBER
DESCRIPTION SYS.XMLTYPETo format the DESCRIBE output use the SET command as follows:
SET LINESIZE 80 SET DESCRIBE DEPTH 2 SET DESCRIBE INDENT ON SET DESCRIBE LINE OFF
To display the settings for the object, use the SHOW command as follows:
SHOW DESCRIBE
DESCRIBE DEPTH 2 LINENUM OFF INDENT ONDESCRIBE employee
Name Null? Type
----------------------------------------- -------- ----------------------
FIRST_NAME VARCHAR2(30)
EMPADDR ADDRESS
STREET VARCHAR2(20)
CITY VARCHAR2(20)
JOB_ID VARCHAR2(20)
SALARY NUMBER(7,2)To create and describe the table des2_table which contains an encrypted column col2, enter
CREATE TABLE des2_table ( col1 VARCHAR2(10), col2 VARCHAR2(15) ENCRYPT, col3 CHAR(5), col4 CHAR(20));
Table createdDESCRIBE des2_table;
Name Null? Type
----------------------------------------- -------- ----------------------
COL1 VARCHAR2(10)
COL2 VARCHAR2(15) ENCRYPT
COL3 CHAR(5)
COL4 CHAR(20)For more information on using the CREATE TYPE command, see your Oracle Database SQL Language Reference.
For information about using the SET DESCRIBE and SHOW DESCRIBE commands, see the SET and SHOW commands.