Execute multiple database queries using a single statement in Java
MySQL allows executing multiple queries in one statement using the semicolon (;) delimiter. However, handling this operation in Java using JDBC may throw exceptions by default.
Method 1: Use connection attributes
To enable multiple query executions, you can specify the allowMultiQueries
connection attribute when establishing the connection:
String dbUrl = "jdbc:mysql:///test?allowMultiQueries=true"; Connection connection = DriverManager.getConnection(dbUrl, username, password);
Method 2: Use stored procedures
Alternatively, you can create a stored procedure in MySQL that contains multiple queries. You can then call the stored procedure from Java using CallableStatement
. An example is as follows:
MySQL stored procedure:
CREATE PROCEDURE multi_query() BEGIN SELECT COUNT(*) AS name_count FROM tbl_mq; INSERT INTO tbl_mq (name) VALUES ('ravi'); SELECT LAST_INSERT_ID(); SELECT * FROM tbl_mq; END;
Java code:
CallableStatement cstmt = connection.prepareCall("{call multi_query()}"); boolean hasMoreResultSets = cstmt.execute(); while (hasMoreResultSets) { ResultSet rs = cstmt.getResultSet(); // 处理结果集 while (rs.next()) { // 处理每一行数据 } hasMoreResultSets = cstmt.getMoreResults(); }
Handle multiple queries
For both methods, you can iterate over the results using the Statement
or CallableStatement
object's getResultSet()
methods. The getMoreResults()
method returns true
to indicate there are more results to process, ensuring you capture all results for multiple queries.
Note:
Remember that DML (Data Manipulation Language) statements like INSERT, UPDATE, and DELETE do not return a result set, so you should handle them individually. When processing result sets, be sure to close ResultSet
and Statement
objects to release resources. It is recommended to use the try-with-resources statement to ensure automatic closing of resources.
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