The listTables() method returns an array of strings,
naming all tables in the current database.
The describeTable() method returns an associative
array of metadata about a table. Specify the name of the table
as a string in the first argument to this method. The second
argument is optional, and names the schema in which the table
exists.
The keys of the associative array returned are the column names of the table. The value corresponding to each column is also an associative array, with the following keys and values:
Table 64. Metadata Fields Returned by describeTable()
| Key | Type | Description |
|---|---|---|
SCHEMA_NAME |
(string) | Name of the database schema in which this table exists. |
TABLE_NAME |
(string) | Name of the table to which this column belongs. |
COLUMN_NAME |
(string) | Name of the column. |
COLUMN_POSITION |
(integer) | Ordinal position of the column in the table. |
DATA_TYPE |
(string) | RDBMS name of the datatype of the column. |
DEFAULT |
(string) | Default value for the column, if any. |
NULLABLE |
(boolean) |
TRUE if the column accepts SQL
NULL's, FALSE if the
column has a NOT NULL
constraint.
|
LENGTH |
(integer) | Length or size of the column as reported by the RDBMS. |
SCALE |
(integer) |
Scale of SQL NUMERIC or
DECIMAL type.
|
PRECISION |
(integer) |
Precision of SQL NUMERIC or
DECIMAL type.
|
UNSIGNED |
(boolean) |
TRUE if an integer-based type is reported as
UNSIGNED.
|
PRIMARY |
(boolean) |
TRUE if the column is part of the primary key of
this table.
|
PRIMARY_POSITION |
(integer) | Ordinal position (1-based) of the column in the primary key. |
IDENTITY |
(boolean) |
TRUE if the column uses an auto-generated value.
|
How the IDENTITY Metadata Field Relates to Specific RDBMSs
The IDENTITY metadata field was chosen as an 'idiomatic' term
to represent a relation to surrogate keys. This field can be
commonly known by the following values:-
IDENTITY- DB2, MSSQLAUTO_INCREMENT- MySQL/MariaDBSERIAL- PostgreSQLSEQUENCE- Oracle
If no table exists matching the table name and optional schema name
specified, then describeTable() returns an empty array.