How to get field length of Oracle

You can obtain the field length in Oracle by using the SELECT query; using the DESCRIBE command; and using the DBMS_METADATA package.

How to get the length of a field in Oracle

In an Oracle database, you can obtain the field length by:

1. Use SELECT to query

 <code class="sql">SELECT data_length FROM user_tab_columns WHERE table_name = 'table_name' AND column_name = 'column_name';</code>

in:

• table_name is the name of the table you want to get the field length.
• column_name is the name of the field you want to get the length.

2. Use the DESCRIBE command

 <code class="sql">DESCRIBE table_name;</code>

This will display information for all fields in the table, including field length.

3. Use the DBMS_METADATA package

 <code class="sql">SELECT length(column_name) FROM user_tab_columns WHERE table_name = 'table_name' AND column_name = 'column_name';</code>

in:

• length() function returns the length of the field.

Example

The following example gets the length of the field first_name in the table employees :

 <code class="sql">SELECT data_length FROM user_tab_columns WHERE table_name = 'employees' AND column_name = 'first_name';</code>

This returns the length of the field first_name , usually 30 characters.

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