SQL Limit

In SQL, the user can implement the Limit clause that can be used to limit the search result. In Oracle, you can use the FETCH FIRST n ROWS ONLY or ROWNUM that performs the same function as Limit. It is instrumental in scenarios where the user wants the data to be arranged sequentially if a large number of records meet the conditions mentioned in the query. So, viewing a limited record at a particular instance may be better.

Some Key Points To Remember When Using Limit

• The limit clause limits the number of records returned by SQL when retrieving a result.
• Ensuring that the clause cannot be implemented in all SQL versions is essential. All SQL versions do not support the limit clause.
• The user can implement the Limit clause using the SQL 2008 OFFSET/FETCH FIRST clauses.
• When implementing the Limit clause, the user should ensure that the limit/offset expression is a non-negative integer.

Syntax to Implement SELECT LIMIT

The syntax to implement the LIMIT keyword in your SELECT statement is as follows:

Parameters or Arguments

1. Exp: It specifies the column or data value the user wants to retrieve from the tables.
2. Tbls: It specifies the table's name to which the columns in the above expression belong. There should at least be one table in the FROM clause, and that table must have the columns of the SELECT statement.
3. WHERE Condn: Adding a WHERE condn in the SQL statement is optional. The purpose is to implement the WHERE clause to retrieve results that meet the mentioned conditions.
4. ORDER BY exp: It is also an exception clause that can be implemented using SQL query. It is implemented in the SELECT LIMIT query to enable users to arrange the records they want to retrieve. The exp contains the column's name and the value used for arranging the records. It can either be ascending or descending.
5. Limit: The keyword is used to specify the number of rows that should be present in the result set. It takes the numerical value as a parameter representing the number of results displayed on implementing the SELECT query.
6. For Example, if LIMIT 10 is implemented, it would return only the first 10 records that satisfy the conditions in the SELECT criteria. This is where it becomes essential to implement the ORDER BY clause so that the user can maintain the order for the results returned by the SELECT query.
7. OFFSET offset_value: It is an optional parameter that can be used within the LIMIT clause. It is used to determine from which record the retrieving process will begin. It decides the first row from where the retrieval is done.

How to Implement the LIMIT Keyword

• The LIMIT keyword sets an upper limit to the results displayed in the return set.
• The user needs to assign a numerical value to the LIMIT keyword. It can range from 0 or any other positive number. If the LIMIT is set to 0, no record will be returned in the result set.
• The user uses the offset value to specify the record from where the data retrieval will begin in the table.
• The Choose Update or DELETE order is suitable o be implemented with the syntax of LIMIT.

Need to Implement the LIMIT Clause

Consider a situation where the developer wants to develop an application that runs over large. The database is very heavy and contains a large number of records that meet the conditions for search and retrieval, increasing the load time. The system designer can reduce the load times by fixing the maximum number of records the application will return. Suppose the maximum number of records displayed in a single search is 20. To enforce the above scenario that ensures the customer needs are met. In such scenarios, the user can implement the LIMIT keyword so that 20 records per tab can be used to limit the data returned from the query.

For Example,

Let us consider a situation where you have a Student table, and to have a better understanding, we will use the Limit clause to retrieve a limited number of results from the result set. We will implement the Limit clause to perform these actions.

The table is as follows:

Implement the SQL query to define and insert the data in the above table:

Output:

Implementing Limit Clause

Output:

Implementing Limit Clause With Order By Clause

Output:

The Limit clause operator can be used when the user wants to retrieve selected results without implementing the WHERE clause in the SQL. The above query will return the top 3 eldest students without requiring them to implement the conditional statements.

Using LIMIT along with OFFSET

LIMIT x OFFSET y means skip the first y entries and then return the following x entries. To implement the OFFSET, the user must implement the ORDER BY clause. The user can only implement the OFFSET by using ORDER. When using OFFSET, the value should be either greater or equal to zero. If it has a negative value, the query will return an error.

or

The above queries will skip the first two entries and return the following 4 entries. The Limit has two parameters in the above query. The first value is regarded as X and is the offset value. It will skip X records; the second parameter is Y; it specifies the next Y record that will be returned.

Output:

Retrieve Nth Highest or Lowest Value From the Table

The limit function determines the highest or lowest value stored in the database.

Now we will look for LIMIT use in finding the highest or lowest value. We need to retrieve the rows with the nth highest or lowest value. We can use the subsequent MySQL LIMIT clause to obtain the desired outcome in that situation.

Syntax:

Output:

The Limit in MySQL with Where

The user can implement the WHERE clause while using the Limit keyword in SQL. It enables the user to specify a condition that should be met by the limit rows produced as the result set from the table.

Output:

Advantages Of Implementing the LIMIT Clause

• The primary function of the Limit Clause is to specify the maximum number of rows present in the result set. It returns the exact maximum rows even in scenarios where the max row count exceeds the number of rows meeting the specified criteria. They are the only row that will be returned from the table even if they meet the condition in the WHERE clause.
• It can also assign the maximum value by implementing a host variable or the value of the SPL input in the local variable.
• If the LIMIT clause is followed by the ORDER BY clause, the records that are retrieved are arranged based on the ORDER BY clause. Since there is no definitive order in which the query results are returned. Therefore, to get the results in a specific order, the user can implement the ORDER BY clause to get a fixed subset of the qualified rows by restricting the order of rows using a specific record arrangement.

Restrictions on the LIMIT clause

There are specific scenarios that restrict the implementation of the LIMIT clause. In the following situations, the user can not implement the LIMIT clause:

• When defining a view.
• The LIMIT clause cannot be implemented in Nested SELECT statements.
• It cannot be implemented with the subqueries other than the subqueries used in the table expression mentioned in the FROM Clause.
• It cannot be used with the Embedded SELECT queries implemented as expressions in a singleton SELECT where (max=1) within an SPL routine where embedded SELECT statements are implemented as expressions.