Passing array parameter in prepare statement - get

问题:

I am facing error java.sql.SQLFeatureNotSupportedException in my prepare statement. I am using Mysql database.

Below is my code.

class tmp {
public static void main(String arg[]) {

    try {
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = DriverManager.getConnection(
                "jdbc:mysql://localhost/sample", "root", "root");
        PreparedStatement pst = conn
                .prepareStatement("select * from userinfo where firstname in(?)");

        String[] Parameter = { "user1", "Administrator" };
        Array sqlArray = conn.createArrayOf("VARCHAR", Parameter);
        pst.setArray(1, sqlArray);
        ResultSet rs = pst.executeQuery();
        while (rs.next()) {
            System.out.println(rs.getInt(1));
        }
    } catch (Exception e) {
        e.printStackTrace();
        }
    }
}

回答1:

For Mysql -

Setting array is not possible in Mysql.

Instead of that you can form a query for (?,?,..) in the loop and same way for setting values.

String[] Parameter = { "user1", "Administrator" };
String query = "select * from userinfo where firstname in (";
String temp = "";

for(i = 0; i < Parameter.length; i++) {
  temp += ",?";
}

temp = temp.replaceFirst(",", "");
temp += ")";
query = query + temp;

PreparedStatement pst = conn.prepareStatement(query);

so query becomes

select * from userinfo where firstname in (?,?)

and pass values also using loop.

For Oracle -

ArrayDescriptor arrayDescriptor = ArrayDescriptor.createDescriptor("CHAR_ARRAY", conn);
String[] Parameter = { "user1", "Administrator" };
java.sql.Array sqlArray = new oracle.sql.ARRAY(arrayDescriptor, conn, content);
.
.
pstmt.setArray(1, sqlArray);

回答2:

Error message is very clear. And MySQL does not support custom data types.

Currently MySQL is supporting only:

1. Numeric Type
2. Date and Time Type
3. String Type

Or, you can use each of the input values as a set of values of IN function in MySQL.

Change your JAVA code as follows:

StringBuilder sbSql = new StringBuilder( 1024 );
sbSql.append( "select * from userinfo where firstname in(" );

for( int i=0; i < Parameter.length; i++ ) {
  if( i > 0 ) sbSql.append( "," );
  sbSql.append( " ?" );
} // for
sbSql.append( " )" );
PreparedStatement pst = conn.prepareStatement( sbSql.toString() );

for( int i=0; i < Parameter.length; i++ ) {
  pst.setString( i+1, Parameter[ i ] );
} // for

ResultSet rs = pst.executeQuery();

回答3:

Convert List to a comma separated String and use it.

Class Tmp {
        public static void main(String arg[]) {

            try {
                Class.forName("com.mysql.jdbc.Driver");
                Connection conn = DriverManager.getConnection(
                        "jdbc:mysql://localhost/sample", "root", "root");

                // Consider this list is already constructed
                List<String> parameter = new ArrayList<String>();
                parameter.add("user1");
                parameter.add("Administrator");

                String parameterStr = "'" + String.join("','", parameter) + "'";
                PreparedStatement pst = conn.prepareStatement("select * from userinfo where firstname in(" + parameterStr + ")");

                ResultSet rs = pst.executeQuery();
                while (rs.next()) {
                    System.out.println(rs.getInt(1));
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }