關於這個table 我可以參考 Oracle 提供的資料
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 ANALYZE SQL statement or the DBMS_STATS package.Related Views
DBA_TAB_COLUMNSdescribes the columns of all tables, views, and clusters in the database.USER_TAB_COLUMNSdescribes the columns of the tables, views, and clusters owned by the current user. This view does not display theOWNERcolumn.
| 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(106) | 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 the right of the decimal point in a number | |
NULLABLE | VARCHAR2(1) | Indicates whether a column allows NULLs. The value is N if there is a NOT NULL constraint on the column or if the column is part of a PRIMARY KEY.The constraint should be in an ENABLE VALIDATE state. | |
COLUMN_ID | NUMBER | Sequence number of the column as created | |
DEFAULT_LENGTH | NUMBER | Length of the default value for the column | |
DATA_DEFAULT | LONG | Default value for the column | |
NUM_DISTINCT | NUMBER | Number of distinct values in the columnFoot 1 | |
LOW_VALUE | RAW(32) | Low value in the columnFootref 1 | |
HIGH_VALUE | RAW(32) | High value in the columnFootref 1 | |
DENSITY | NUMBER | Density of the columnFootref 1 | |
NUM_NULLS | NUMBER | Number of NULLs in the column | |
NUM_BUCKETS | NUMBER | Number of buckets in the histogram for the column Note: The number of buckets in a histogram is specified in the SIZEparameter of the ANALYZE SQL statement. However, Oracle Database 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 Database 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 | Date on which this column was most recently analyzed | |
SAMPLE_SIZE | NUMBER | Sample size used in analyzing this column | |
CHARACTER_SET_NAME | VARCHAR2(44) | Name of the character set:
| |
CHAR_COL_DECL_LENGTH | NUMBER | Declaration length of the character type column | |
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) | Indicates whether statistics were entered directly by the user (YES) or not (NO) | |
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_USED | VARCHAR2(1) | Indicates that the column uses BYTE length semantics (B) or CHAR length semantics (C), or whether the datatype is not any of the following (NULL):
| |
V80_FMT_IMAGE | VARCHAR2(3) | Indicates whether the column data is in release 8.0 image format (YES) or not (NO) | |
DATA_UPGRADED | VARCHAR2(3) | Indicates whether the column data has been upgraded to the latest type version format (YES) or not (NO) | |
HISTOGRAM | VARCHAR2(15) | Indicates existence/type of histogram:
|
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