The rowcount function is usually used to obtain the query result set or the number of rows affected by SQL operations in the database. The specific usage and syntax may vary depending on the database management system, and the corresponding usage and operation need to be carried out according to the specific system. Detailed introduction: 1. The rowcount function in MySQL is usually used to obtain the number of rows affected by the most recently executed SELECT, INSERT, UPDATE or DELETE query, etc.
The rowcount function is usually used to get the number of rows in the SQL query result set. The usage of the rowcount function may vary in different database management systems. Below I will introduce Usage of rowcount function in some popular database systems.
1. Usage of rowcount function in MySQL:
In MySQL, the rowcount function is usually used to obtain the impact of the most recently executed SELECT, INSERT, UPDATE or DELETE query. number of rows.
For SELECT queries, you can use the following statement to get the number of rows in the result set:
SELECT FOUND_ROWS();
For INSERT, UPDATE, and DELETE queries, you can use the following statements to get the number of affected rows:
SELECT ROW_COUNT();
This way you can easily get the impact of the query or operation on the number of rows in the database.
2. Usage of rowcount function in SQL Server:
In SQL Server, you can use the @@ROWCOUNT variable to obtain the number of the most recently executed T-SQL statement. Number of rows affected.
For example, you can use the following code after the query statement to obtain the number of rows in the query result set:
SELECT @@ROWCOUNT;
After executing INSERT, UPDATE, and DELETE operations, you can also use @@ROWCOUNT to obtain Number of rows affected.
3. Usage of rowcount function in Oracle:
In Oracle database, you can use the SQL%ROWCOUNT variable to obtain the most recently executed SELECT or DML Number of rows affected by statements (INSERT, UPDATE, DELETE).
For example, you can use the following code after the query statement to get the number of rows in the query result set:
SELECT COUNT(*) FROM your_table_name;
For INSERT, UPDATE, and DELETE operations, you can use the SQL%ROWCOUNT variable after executing the statement. to get the number of affected rows.
4. Usage of rowcount function in PostgreSQL:
In PostgreSQL, you can use the GET DIAGNOSTICS system function to obtain the number of rows affected by a SQL query or operation.
For example, you can use the following code after the query statement to get the number of rows in the query result set:
GET DIAGNOSTICS rows_affected = ROW_COUNT;
For INSERT, UPDATE, and DELETE operations, you can use GET DIAGNOSTICS after executing the statement. Number of rows affected.
In general, the rowcount function is usually used to obtain the query result set or SQL The number of rows in the database affected by the operation. The specific usage and syntax may vary depending on the database management system, and the corresponding usage and operation need to be carried out according to the specific system.
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