DBA_TAB_COLUMNS

DBA_TAB_COLUMNS displays the columns of tables. Each column of a table in the database has a row in DBA_TAB_COLUMNS. It is accessible only to users with system administrator rights.

**Table 1** DBA_TAB_COLUMNS columns
Name	Type	Description
owner	character varying(64)	Table owner
table_name	character varying(64)	Table name
column_name	character varying(64)	Column name
data_type	character varying(128)	Data type of the column
column_id	integer	Sequence number of the column when the table is created
data_length	integer	Length of the column in the unit of bytes
comments	text	Comments
avg_col_len	numeric	Average length of a column in the unit of bytes
nullable	bpchar	Whether the column can be empty. For the primary key constraint and non-null constraint, the value is n.
data_precision	integer	Indicates the precision of the data type. This parameter is valid for the numeric data type, however its value is NULL for other types.
data_scale	integer	Number of decimal places. This parameter is valid for the numeric data type. For other data types, the value of this parameter is 0.
char_length	numeric	Column length (in the unit of bytes) which is valid only for varchar, nvarchar2, bpchar, and char types.