USER_TAB_COLUMNS

The USER_TAB_COLUMNS provides information about the columns of the tables, views, and clusters owned by the current user.

Column name Data type Description
TABLE_NAME VARCHAR2(128) The name of the table, view, or cluster.
Always NOT NULL.
COLUMN_NAME VARCHAR2(128) The column name.
Always NOT NULL.
DATA_TYPE VARCHAR2(128) The data type of the column.
DATA_TYPE_MOD VARCHAR2(3) The data type modifier of the column.
DATA_TYPE_OWNER VARCHAR2(128) The owner of the column data type.
DATA_LENGTH NUMBER The length of the column, in bytes.
Always NOT NULL.
DATA_PRECISION NUMBER The length of the column, expressed in decimal digits for the NUMBER data type, binary digits for the FLOAT data type, or NULL for all other data types.
DATA_SCALE NUMBER The digits to the right of the decimal point in a number.
NULLABLE VARCHAR2(1) Specifies whether the column can contain NULL values.
The possible values are:
  • N - The column can’t contain NULL values, because it is part of a PRIMARY KEY or the constraint on the column is NOT NULL.
  • Y - The column can contain NULL values.
COLUMN_ID NUMBER The sequence number of the column.
DEFAULT_LENGTH NUMBER The length of the column’s default value.
DATA_DEFAULT LONG The default value of the column.
NUM_DISTINCT NUMBER The number of distinct values in the column.
The column is retained for backward compatibility with Oracle7.
LOW_VALUE RAW(1000) The lowest value stored in the column.
The column is retained for backward compatibility with Oracle7.
HIGH_VALUE RAW(1000) The highest value stored in the column.
The column is retained for backward compatibility with Oracle7.
DENSITY NUMBER The uniqueness of values in a column.
  • If a histogram exists on the column, it displays the selectivity of values spanning fewer than 2 histogram endpoints.
  • If no histogram exists, the value is computed as 1/NUM_DISTINCT.

The column is retained for backward compatibility with Oracle7.
NUM_NULLS NUMBER The number of NULL values in the column.
NUM_BUCKETS NUMBER The number of buckets used in a column histogram.
LAST_ANALYZED DATE The date when the column was most recently analyzed.
SAMPLE_SIZE NUMBER The number of rows used when analyzing the column.
CHARACTER_SET_NAME VARCHAR2(44) The name of the character set.
The possible values are:
  • CHAR_CS
  • NCHAR_CS
CHAR_COL_DECL_LENGTH NUMBER The declared length of a character type column.
GLOBAL_STATS VARCHAR2(3) Specifies whether statistics are gathered or incrementally maintained (YES) or not (NO).
USER_STATS VARCHAR2(3) Specifies whether statistics were entered directly by the user (YES) or not (NO).
AVG_COL_LEN NUMBER The average length of the column, in bytes.
CHAR_LENGTH NUMBER The length of the actual data stored in a character column, in characters.
CHAR_USED VARCHAR2(1) The unit of length used for a character column.
The possible values are:
  • B - The length is measured in bytes.
  • C - The length is measured in characters.
V80_FMT_IMAGE VARCHAR2(3) The image format used for storing data.
The possible values are:
  • YES
  • NO
  • NONE
DATA_UPGRADED VARCHAR2(3) Specifies whether the column data has been upgraded to a newer database format (YES) or not (NO).
HISTOGRAM VARCHAR2(15) Specifies whether a histogram exists for the column and, if so, displays the type of the histogram.
The possible values are:
  • NONE
  • FREQUENCY
  • TOP-FREQUENCY
  • HEIGHT BALANCED
  • HYBRID
DEFAULT_ON_NULL VARCHAR2(3) Specifies whether the column has the DEFAULT ON NULL semantics (YES) or not (NO).
IDENTITY_COLUMN VARCHAR2(3) Specifies whether the column is an identity column (YES) or not (NO).
EVALUATION_EDITION VARCHAR2(128) The name of the edition in which editioned objects referenced in an expression column are resolved.
UNUSABLE_BEFORE VARCHAR2(128) The name of the oldest edition in which the column becomes usable.
UNUSABLE_BEGINNING VARCHAR2(128) The name of the oldest edition in which the column becomes perpetually unusable.
COLLATION VARCHAR2(100) The collation of the column. Only applies to columns with character data types.