我创建此代码是为了允许我计算表中的行数。但是,我无法返回计数的数字,并显示错误“无法从结果类型为 void 的方法返回值”。有人可以告诉我我的错误在哪里吗?多谢!
public void num() throws Exception {
try {
// This will load the MySQL driver, each DB has its own driver
Class.forName("com.mysql.jdbc.Driver");
// Setup the connection with the DB
connect = DriverManager.getConnection("jdbc:mysql://localhost/testdb?"
+ "user=root&password=");
// Statements allow to issue SQL queries to the database
statement = connect.createStatement();
resultSet = statement.executeQuery("select * from testdb.emg");
int count = 0;
while (resultSet.next()) {
count++;
}
return count;
} catch (Exception e) {
}
尝试下面的代码
public int num() throws Exception {
try {
// This will load the MySQL driver, each DB has its own driver
Class.forName("com.mysql.jdbc.Driver");
// Setup the connection with the DB
connect = DriverManager.getConnection("jdbc:mysql://localhost/testdb?"
+ "user=root&password=");
// Statements allow to issue SQL queries to the database
statement = connect.createStatement();
resultSet = statement.executeQuery("select count(*) from testdb.emg");
while (resultSet.next()) {
return resultSet.getInt(1);
}
} catch (Exception e) {
}
以下是错误
-
public void num() throws Exception {
应该
public int num() throws Exception {
为了计算总行数,您应该使用查询select count(*) from testdb.emg
如果有任何问题请告诉我。
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