Top 10 Results: How to Query MySQL for the First Ten Rows?（mysql查询前十条）
MySQL is one of the most popular database management systems in the world, and is used by many businesses and organizations. If you want to get the first ten rows from a given database table in MySQL, there are several ways to do so. In this article, we’ll share the top 10 methods that you can use to query MySQL for the first ten rows.
1. Select the Top 10 Rows With the LIMIT Clause:
The LIMIT clause allows you to limit the number of rows returned in a result set. You can use it to select only the first 10 rows from a table, like this:
SELECT * FROM table_name LIMIT 10;
2. Select the Top 10 Rows With an ORDER BY Clause:
If you want to get the top 10 rows from a table ordered on a specific column, you can use the ORDER BY clause with the LIMIT clause. For example, to get the top 10 rows ordered by a column called “amount”, you can use the following query:
SELECT * FROM table_name
ORDER BY amount LIMIT 10;
3. Select the Top 10 Rows With an OFFSET Clause:
Another way to select only the first 10 rows from a table is to use the OFFSET clause with the LIMIT clause. The OFFSET clause allows you to skip a certain number of rows before selecting rows from the table. For example, to select the top 10 rows from a table, you can use the following query:
SELECT * FROM table_name
LIMIT 10 OFFSET 0;
4. Select the Top 10 Rows With a Subquery:
You can also select the top 10 rows from a table using a subquery. A subquery is a query that is nested inside another query. For example, to select the top 10 rows from a table, you can use the following query:
SELECT * FROM table_name
WHERE id IN (
SELECT id FROM table_name
LIMIT 10
);
5. Select the Top 10 Rows With a CTE:
Another way to select the top 10 rows from a table is to use a common table expression (CTE). A CTE is a temporary named result set that is defined within the execution scope of a single SELECT statement. To use a CTE to select the top 10 rows from a table, you can use the following query:
WITH top_10 AS (
SELECT * FROM table_name
LIMIT 10
)
SELECT * FROM top_10;
6. Select the Top 10 Rows With the Row_Number() Function:
The row_number() function is a window function in MySQL that assigns a sequential number starting from one to each row in a partition of a result set. You can use this function to select the top 10 rows from a table like this:
SELECT *
FROM (
SELECT *, ROW_NUMBER() OVER (ORDER BY id) AS rank
FROM table_name
) t
WHERE rank
7. Select the Top 10 Rows With a Correlated Subquery:
A correlated subquery is a subquery that is evaluated once for each row returned by the outer query. You can use this technique to select the top 10 rows from a table like this:
SELECT *
FROM table_name t1
WHERE (
SELECT COUNT(*)
FROM table_name t2
WHERE t2.id
)
8. Select the Top 10 Rows With the Rank() Function:
The rank() function assigns a rank to each row in a partition of a result set. You can use this to select the top 10 rows from a table like this:
SELECT *
FROM (
SELECT *, RANK() OVER (ORDER BY id) AS rank
FROM table_name
) t
WHERE rank
9. Select the Top 10 Rows With the Dense_rank() Function:
The dense_rank() function is similar to the rank() function, except that it assigns the same rank to rows with identical values. You can use this to select the top 10 rows from a table like this:
SELECT *
FROM (
SELECT *, DENSE_RANK() OVER (ORDER BY id) AS rank
FROM table_name
) t
WHERE rank
10. Select the Top 10 Rows With a User-Defined Variable:
You can also use a user-defined variable to select the top 10 rows from a table. A user-defined variable is a special type of variable that you can use in a MySQL query. To select the top 10 rows from a table using a user-defined variable, you can use the following query:
SET @rank = 0;
SELECT * FROM
(
SELECT *, @rank := @rank + 1 AS rank
FROM table_name
ORDER BY id
) t
WHERE rank
These are the top 10 methods that you can use to query MySQL for the first ten rows. Depending on your requirements, you should select the best method for your query.
