两个表的联合和计数与条件

Question

I have to write the following query in zend-framework2

select count(*) from  
(
    select * from table1
    UNION
    select * from table2
)
as a
where col1 = condition1 and col2 = condition2;

I have done union of two tables using -

$select1 = new Select('table1');
$select2 = new Select("table2");
$select1->combine($select2);

I don't know how to give an alias after doing the union of two tables and how to get the count of data.

Answer 1

After $select1->combine($select2); -

$sql = new Sql($this->tableGateway->adapter);
$select_string = $sql->getSqlStringForSqlObject($select1);

$sql_string = 'SELECT * FROM (' . $select_string . ') AS select_union WHERE col1 = condition1 and col2 = condition2';
$statement = $this->tableGateway->adapter->createStatement($sql_string);
$resultSet = $statement->execute();
$total_records = count($resultSet);

$resultSet gives data.

$total_records gives total no. of records.