SQL tutorial 71: LPAD and RPAD SQL Function By Manish Sharma RebellionRider

Summary

In this SQL tutorial, Manish from RebellionRider.com explains the LPAD and RPAD functions, which pad expressions with special characters to a specific length. The LPAD function adds padding to the left of the expression, while RPAD adds it to the right. Through practical examples, Manish demonstrates how to use these functions with character strings and data from columns. The tutorial emphasizes customizing padding characters and setting desired string lengths. By the end, viewers will understand how to apply LPAD and RPAD in their own SQL queries.

Takeaways

• 😀 LPAD and RPAD are SQL functions used to pad expressions with special characters to a specified length.
• 😀 LPAD adds padding to the left side of a string, while RPAD adds padding to the right side.
• 😀 The syntax for both functions is similar: `LPAD(expression, length, padding-expression)` and `RPAD(expression, length, padding-expression)`.
• 😀 The first parameter (`expression/column name`) is the value to be padded, which can be a string or a column value.
• 😀 The second parameter (`length`) defines the total length of the result after padding, including both the original expression and the padding characters.
• 😀 The third parameter (`padding-expression`) is the character or string used to pad the original expression; it defaults to a space if not specified.
• 😀 Padding characters can be any special character like asterisks, hashes, or dollar signs, or even mathematical expressions.
• 😀 An example of LPAD: `SELECT LPAD('RebellionRider', 20, '#')` pads the string 'RebellionRider' with six '#' characters on the left to make the total length 20.
• 😀 An example of RPAD: `SELECT RPAD('RebellionRider', 20, '#')` pads the string 'RebellionRider' with six '#' characters on the right to make the total length 20.
• 😀 The LPAD and RPAD functions can also be used with column values, as demonstrated by padding the `salary` column in the employees table with asterisks.
• 😀 Understanding how padding functions work helps in formatting output for better readability and presentation in SQL queries.

Q & A

What is the purpose of the LPAD function in SQL?

The LPAD function in SQL is used to pad an expression with a specified character or string to the left side, making the total length of the expression equal to a given value.

What does the 'length' parameter in the LPAD and RPAD functions represent?

The 'length' parameter specifies the total length of the returned value, including both the original expression and any padding characters added.

What is the default padding character in the LPAD and RPAD functions?

The default padding character is a single blank space. However, you can specify any other character or string to use for padding.

What is the difference between LPAD and RPAD functions?

The LPAD function pads the expression with the specified character(s) on the left side, while the RPAD function pads the expression on the right side.

Can the LPAD and RPAD functions be used with columns in a table?

Yes, both LPAD and RPAD can be used with column values, such as the 'salary' column in the employees table, to pad the values in those columns.

In the example SELECT LPAD ('RebellionRider', 20, '#') FROM dual;, what does the result represent?

In this example, the string 'RebellionRider' is padded with 6 hash signs (#) on the left side to make the total length of the result 20 characters.

What is the significance of the 'dual' table in the SQL examples?

The 'dual' table is a special, built-in table in Oracle databases that is commonly used when a query requires a dummy table for functions that do not need data from any actual table.

What happens if the padding length exceeds the specified 'length' value?

If the total length of the expression with padding exceeds the specified length, the expression will be truncated to fit the specified length, ensuring the result does not exceed the defined total length.

In the query SELECT LPAD (salary, 20, '*') FROM employees;, what does the asterisk (*) represent?

In this query, the asterisk (*) is the padding character, and it is added to the left side of the values in the 'salary' column to make each result 20 characters long.

How would you explain the usage of LPAD and RPAD in real-world scenarios?

LPAD and RPAD can be useful in formatting outputs for reports or generating fixed-width strings for data exports. For example, they can be used to align text in columns or to pad numeric values to a consistent length in database exports.