ALL_TAB_COLUMNS

ALL_TAB_COLUMNS describes the columns of the tables, views, and clusters accessible to the current user. To gather statistics for this view, use the SQL ANALYZE statement or the DBMS_STATS package.

Related Views

• DBA_TAB_COLUMNS describes the columns of all tables, views, and clusters in the database.
• USER_TAB_COLUMNS describes the columns of the tables, views, and clusters owned by the current user. This view does not display the OWNER column.

  Column	Datatype	NULL	Description
  OWNER	VARCHAR2(30)	NOT NULL	Owner of the table, view, or cluster
  TABLE_NAME	VARCHAR2(30)	NOT NULL	Name of the table, view, or cluster
  COLUMN_NAME	VARCHAR2(30)	NOT NULL	Column name
  DATA_TYPE	VARCHAR2(30)		Datatype of the column
  DATA_TYPE_MOD	VARCHAR2(3)		Datatype modifier of the column
  DATA_TYPE_OWNER	VARCHAR2(30)		Owner of the datatype of the column
  DATA_LENGTH	NUMBER	NOT NULL	Length of the column in bytes
  DATA_PRECISION	NUMBER		Decimal precision for NUMBER datatype; binary precision for FLOAT datatype, null for all other datatypes
  DATA_SCALE	NUMBER		Digits to right of decimal point in a number
  NULLABLE	VARCHAR2(1)		Specifies whether a column allows NULLs. Value is N if there is a NOT NULL constraint on the column or if the column is part of a PRIMARY KEY.
  COLUMN_ID	NUMBER	NOT NULL	Sequence number of the column as created
  DEFAULT_LENGTH	NUMBER		Length of default value for the column
  DATA_DEFAULT	LONG		Default value for the column
  NUM_DISTINCT	NUMBER		These columns remain for backward compatibility with Oracle7. This information is now in the {TAB|PART}_COL_STATISTICS views. This view now picks up these values from HIST_HEAD$ rather than COL$.
  LOW_VALUE	RAW(32)
  HIGH_VALUE	RAW(32)
  DENSITY	NUMBER
  NUM_NULLS	NUMBER		Number of nulls in the column
  NUM_BUCKETS	NUMBER		The number of buckets in histogram for the column Note: The number of buckets in a histogram is specified in the SIZE parameter of the SQL statement ANALYZE. However, Oracle does not create a histogram with more buckets than the number of rows in the sample. Also, if the sample contains any values that are very repetitious, Oracle creates the specified number of buckets, but the value indicated by this column may be smaller because of an internal compression algorithm.
  LAST_ANALYZED	DATE		The date on which this column was most recently analyzed
  SAMPLE_SIZE			The sample size used in analyzing this column
  CHARACTER_SET_NAME	VARCHAR2(44)		The name of the character set: CHAR_CS or NCHAR_CS
  CHAR_COL_DECL_LENGTH	NUMBER		The length
  GLOBAL_STATS	VARCHAR2(3)		For partitioned tables, indicates whether column statistics were collected for the table as a whole (YES) or were estimated from statistics on underlying partitions and subpartitions (NO).
  USER_STATS	VARCHAR2(3)		Were the statistics entered directly by the user?
  AVG_COL_LEN	NUMBER		Average length of the column (in bytes)
  CHAR_LENGTH	NUMBER		Displays the length of the column in characters. This value only applies to the following datatypes: CHAR VARCHAR2 NCHAR NVARCHAR
  CHAR_USED	VARCHAR2(1)		B | C. B indicates that the column uses BYTE length semantics. C indicates that the column uses CHAR length semantics. NULL indicates the datatype is not any of the following: CHAR VARCHAR2 NCHAR NVARCHAR2