When working with databases, it’s common to have tables with identity columns. These columns automatically generate unique values for each new record inserted into the table. However, when using SQL Loader to load data into these tables, we need a slightly different approach to handle identity columns. In this blog post, we will explore how to load data into tables with identity columns using SQL Loader.

What is an identity column?

An identity column is a column in a database table that automatically generates a unique value for each new row inserted. It provides a convenient way to ensure data integrity and avoid conflicts when inserting new records. Identity columns are commonly used as primary keys in tables.

Using SQL Loader to load data

SQL Loader is a powerful command-line tool provided by Oracle for loading data into Oracle databases. It’s efficient and fast, making it a popular choice for data import tasks. However, when working with tables that have identity columns, SQL Loader needs some additional instructions to handle these columns correctly.

To load data into tables with identity columns using SQL Loader, follow these steps:

1. Create a control file: A control file is a text file that specifies the format of the data being loaded and provides instructions to SQL Loader. In the control file, define the layout of your data file, including the identity column.

2. Specify the column list in the control file: In the control file, explicitly mention all the columns except for the identity column. This ensures that the identity column is not included when loading data.

Example control file (example.ctl):

LOAD DATA
INFILE 'data.csv'
INTO TABLE my_table
FIELDS TERMINATED BY ','
(IDENTITY_COLUMN, COLUMN1, COLUMN2)

1. Create a data file: The data file contains the actual data you want to load into the table. Make sure the data file is properly formatted and aligned with the control file.

Example data file (data.csv):

123,Value1,Value2
124,Value3,Value4
125,Value5,Value6

1. Run SQL Loader: Open a terminal or command prompt, navigate to the directory where the control file and data file are located, and run SQL Loader using the control file.

sqlldr username/password@database control=example.ctl

SQL Loader will read the data from the data file, skip the identity column defined in the control file, and load the remaining columns into the table.

Conclusion

Loading data into tables with identity columns using SQL Loader requires a bit of extra configuration in the control file. By explicitly excluding the identity column and specifying the remaining columns, you can successfully load data into these tables without any conflicts. SQL Loader is a powerful tool for efficient data loading, and with the right control file, you can handle tables with identity columns seamlessly.

#sqlloader #identitycolumns