SQL Abstraction

Zend\Db\Sql is a SQL abstraction layer for building platform-specific SQL queries via an object-oriented API. The end result of a Zend\Db\Sql object will be to either produce a Statement and ParameterContainer that represents the target query, or a full string that can be directly executed against the database platform. To achieve this, Zend\Db\Sql objects require a Zend\Db\Adapter\Adapter object in order to produce the desired results.

Quick start

There are four primary tasks associated with interacting with a database defined by Data Manipulation Language (DML): selecting, inserting, updating, and deleting. As such, there are four primary classes that developers can interact with in order to build queries in the Zend\Db\Sql namespace: Select, Insert, Update, and Delete.

Since these four tasks are so closely related and generally used together within the same application, the Zend\Db\Sql\Sql class helps you create them and produce the result you are attempting to achieve.

use Zend\Db\Sql\Sql;

$sql    = new Sql($adapter);
$select = $sql->select(); // returns a Zend\Db\Sql\Select instance
$insert = $sql->insert(); // returns a Zend\Db\Sql\Insert instance
$update = $sql->update(); // returns a Zend\Db\Sql\Update instance
$delete = $sql->delete(); // returns a Zend\Db\Sql\Delete instance

As a developer, you can now interact with these objects, as described in the sections below, to customize each query. Once they have been populated with values, they are ready to either be prepared or executed.

To prepare (using a Select object):

use Zend\Db\Sql\Sql;

$sql    = new Sql($adapter);
$select = $sql->select();
$select->from('foo');
$select->where(['id' => 2]);

$statement = $sql->prepareStatementForSqlObject($select);
$results = $statement->execute();

To execute (using a Select object)

use Zend\Db\Sql\Sql;

$sql    = new Sql($adapter);
$select = $sql->select();
$select->from('foo');
$select->where(['id' => 2]);

$selectString = $sql->buildSqlString($select);
$results = $adapter->query($selectString, $adapter::QUERY_MODE_EXECUTE);

Zend\\Db\\Sql\\Sql objects can also be bound to a particular table so that in obtaining a Select, Insert, Update, or Delete instance, the object will be seeded with the table:

use Zend\Db\Sql\Sql;

$sql    = new Sql($adapter, 'foo');
$select = $sql->select();
$select->where(['id' => 2]); // $select already has from('foo') applied

Common interfaces for SQL implementations

Each of these objects implements the following two interfaces:

interface PreparableSqlInterface
{
     public function prepareStatement(Adapter $adapter, StatementInterface $statement) : void;
}

interface SqlInterface
{
     public function getSqlString(PlatformInterface $adapterPlatform = null) : string;
}

Use these functions to produce either (a) a prepared statement, or (b) a string to execute.

Select

Zend\Db\Sql\Select presents a unified API for building platform-specific SQL SELECT queries. Instances may be created and consumed without Zend\Db\Sql\Sql:

use Zend\Db\Sql\Select;

$select = new Select();
// or, to produce a $select bound to a specific table
$select = new Select('foo');

If a table is provided to the Select object, then from() cannot be called later to change the name of the table.

Once you have a valid Select object, the following API can be used to further specify various select statement parts:

class Select extends AbstractSql implements SqlInterface, PreparableSqlInterface
{
    const JOIN_INNER = 'inner';
    const JOIN_OUTER = 'outer';
    const JOIN_LEFT = 'left';
    const JOIN_RIGHT = 'right';
    const SQL_STAR = '*';
    const ORDER_ASCENDING = 'ASC';
    const ORDER_DESCENDING = 'DESC';

    public $where; // @param Where $where

    public function __construct(string|array|TableIdentifier $table = null);
    public function from(string|array|TableIdentifier $table) : self;
    public function columns(array $columns, bool $prefixColumnsWithTable = true) : self;
    public function join(string|array $name, string $on, string|array $columns = self::SQL_STAR, string $type = self::JOIN_INNER) : self;
    public function where(Where|callable|string|array|PredicateInterface $predicate, string $combination = Predicate\PredicateSet::OP_AND) : self;
    public function group(string|array $group);
    public function having(Having|callable|string|array $predicate, string $combination = Predicate\PredicateSet::OP_AND) : self;
    public function order(string|array $order) : self;
    public function limit(int $limit) : self;
    public function offset(int $offset) : self;
}

from()

// As a string:
$select->from('foo');

// As an array to specify an alias
// (produces SELECT "t".* FROM "table" AS "t")
$select->from(['t' => 'table']);

// Using a Sql\TableIdentifier:
// (same output as above)
$select->from(['t' => new TableIdentifier('table')]);

columns()

// As an array of names
$select->columns(['foo', 'bar']);

// As an associative array with aliases as the keys
// (produces 'bar' AS 'foo', 'bax' AS 'baz')
$select->columns(['foo' => 'bar', 'baz' => 'bax']);

join()

$select->join(
    'foo',              // table name
    'id = bar.id',      // expression to join on (will be quoted by platform object before insertion),
    ['bar', 'baz'],     // (optional) list of columns, same requirements as columns() above
    $select::JOIN_OUTER // (optional), one of inner, outer, left, right also represented by constants in the API
);

$select
    ->from(['f' => 'foo'])     // base table
    ->join(
        ['b' => 'bar'],        // join table with alias
        'f.foo_id = b.foo_id'  // join expression
    );

where(), having()

Zend\Db\Sql\Select provides bit of flexibility as it regards to what kind of parameters are acceptable when calling where() or having(). The method signature is listed as:

/**
 * Create where clause
 *
 * @param  Where|callable|string|array $predicate
 * @param  string $combination One of the OP_* constants from Predicate\PredicateSet
 * @return Select
 */
public function where($predicate, $combination = Predicate\PredicateSet::OP_AND);

If you provide a Zend\Db\Sql\Where instance to where() or a Zend\Db\Sql\Having instance to having(), any previous internal instances will be replaced completely. When either instance is processed, this object will be iterated to produce the WHERE or HAVING section of the SELECT statement.

If you provide a PHP callable to where() or having(), this function will be called with the Select's Where/Having instance as the only parameter. This enables code like the following:

$select->where(function (Where $where) {
    $where->like('username', 'ralph%');
});

If you provide a string, this string will be used to create a Zend\Db\Sql\Predicate\Expression instance, and its contents will be applied as-is, with no quoting:

// SELECT "foo".* FROM "foo" WHERE x = 5
$select->from('foo')->where('x = 5');

If you provide an array with integer indices, the value can be one of:

In either case, the instances are pushed onto the Where stack with the $combination provided (defaulting to AND).

As an example:

// SELECT "foo".* FROM "foo" WHERE x = 5 AND y = z
$select->from('foo')->where(['x = 5', 'y = z']);

If you provide an associative array with string keys, any value with a string key will be cast as follows:

PHP value Predicate type
null Predicate\IsNull
array Predicate\In
string Predicate\Operator, where the key is the identifier.

As an example:

// SELECT "foo".* FROM "foo" WHERE "c1" IS NULL AND "c2" IN (?, ?, ?) AND "c3" IS NOT NULL
$select->from('foo')->where([
    'c1' => null,
    'c2' => [1, 2, 3],
    new \Zend\Db\Sql\Predicate\IsNotNull('c3'),
]);

As another example of complex queries with nested conditions e.g.

SELECT * WHERE (column1 is null or column1 = 2) AND (column2 = 3)

you need to use the nest() and unnest() methods, as follows:

$select->where->nest() // bracket opened
    ->isNull('column1')
    ->or
    ->equalTo('column1', '2')
    ->unnest();  // bracket closed
    ->equalTo('column2', '3');

order()

$select = new Select;
$select->order('id DESC'); // produces 'id' DESC

$select = new Select;
$select
    ->order('id DESC')
    ->order('name ASC, age DESC'); // produces 'id' DESC, 'name' ASC, 'age' DESC

$select = new Select;
$select->order(['name ASC', 'age DESC']); // produces 'name' ASC, 'age' DESC

limit() and offset()

$select = new Select;
$select->limit(5);   // always takes an integer/numeric
$select->offset(10); // similarly takes an integer/numeric

Insert

The Insert API:

class Insert implements SqlInterface, PreparableSqlInterface
{
    const VALUES_MERGE = 'merge';
    const VALUES_SET   = 'set';

    public function __construct(string|TableIdentifier $table = null);
    public function into(string|TableIdentifier $table) : self;
    public function columns(array $columns) : self;
    public function values(array $values, string $flag = self::VALUES_SET) : self;
}

As with Select, the table may be provided during instantiation or via the into() method.

columns()

$insert->columns(['foo', 'bar']); // set the valid columns

values()

// The default behavior of values is to set the values;
// successive calls will not preserve values from previous calls.
$insert->values([
    'col_1' => 'value1',
    'col_2' => 'value2',
]);
// To merge values with previous calls, provide the appropriate flag:
$insert->values(['col_2' => 'value2'], $insert::VALUES_MERGE);

Update

class Update
{
    const VALUES_MERGE = 'merge';
    const VALUES_SET   = 'set';

    public $where; // @param Where $where
    public function __construct(string|TableIdentifier $table = null);
    public function table(string|TableIdentifier $table) : self;
    public function set(array $values, string $flag = self::VALUES_SET) : self;
    public function where(Where|callable|string|array|PredicateInterface $predicate, string $combination = Predicate\PredicateSet::OP_AND) : self;
}

set()

$update->set(['foo' => 'bar', 'baz' => 'bax']);

where()

See the section on Where and Having.

Delete

class Delete
{
    public $where; // @param Where $where

    public function __construct(string|TableIdentifier $table = null);
    public function from(string|TableIdentifier $table);
    public function where(Where|callable|string|array|PredicateInterface $predicate, string $combination = Predicate\PredicateSet::OP_AND) : self;
}

where()

See the section on Where and Having.

Where and Having

In the following, we will talk about Where; note, however, that Having utilizes the same API.

Effectively, Where and Having extend from the same base object, a Predicate (and PredicateSet). All of the parts that make up a WHERE or HAVING clause that are AND'ed or OR'd together are called predicates. The full set of predicates is called a PredicateSet. A Predicate generally contains the values (and identifiers) separate from the fragment they belong to until the last possible moment when the statement is either prepared (parameteritized) or executed. In parameterization, the parameters will be replaced with their proper placeholder (a named or positional parameter), and the values stored inside an Adapter\ParameterContainer. When executed, the values will be interpolated into the fragments they belong to and properly quoted.

In the Where/Having API, a distinction is made between what elements are considered identifiers (TYPE_IDENTIFIER) and which are values (TYPE_VALUE). There is also a special use case type for literal values (TYPE_LITERAL). All element types are expressed via the Zend\Db\Sql\ExpressionInterface interface.

Literals

In ZF 2.1, an actual Literal type was added. Zend\Db\Sql now makes the distinction that literals will not have any parameters that need interpolating, while Expression objects might have parameters that need interpolating. In cases where there are parameters in an Expression, Zend\Db\Sql\AbstractSql will do its best to identify placeholders when the Expression is processed during statement creation. In short, if you don't have parameters, use Literal objects.

The Where and Having API is that of Predicate and PredicateSet:

// Where & Having extend Predicate:
class Predicate extends PredicateSet
{
    public $and;
    public $or;
    public $AND;
    public $OR;
    public $NEST;
    public $UNNEST;

    public function nest() : Predicate;
    public function setUnnest(Predicate $predicate) : void;
    public function unnest() : Predicate;
    public function equalTo(
        int|float|bool|string $left,
        int|float|bool|string $right,
        string $leftType = self::TYPE_IDENTIFIER,
        string $rightType = self::TYPE_VALUE
    ) : self;
    public function notEqualTo(
        int|float|bool|string $left,
        int|float|bool|string $right,
        string $leftType = self::TYPE_IDENTIFIER,
        string $rightType = self::TYPE_VALUE
    ) : self;
    public function lessThan(
        int|float|bool|string $left,
        int|float|bool|string $right,
        string $leftType = self::TYPE_IDENTIFIER,
        string $rightType = self::TYPE_VALUE
    ) : self;
    public function greaterThan(
        int|float|bool|string $left,
        int|float|bool|string $right,
        string $leftType = self::TYPE_IDENTIFIER,
        string $rightType = self::TYPE_VALUE
    ) : self;
    public function lessThanOrEqualTo(
        int|float|bool|string $left,
        int|float|bool|string $right,
        string $leftType = self::TYPE_IDENTIFIER,
        string $rightType = self::TYPE_VALUE
    ) : self;
    public function greaterThanOrEqualTo(
        int|float|bool|string $left,
        int|float|bool|string $right,
        string $leftType = self::TYPE_IDENTIFIER,
        string $rightType = self::TYPE_VALUE
    ) : self;
    public function like(string $identifier, string $like) : self;
    public function notLike(string $identifier, string $notLike) : self;
    public function literal(string $literal) : self;
    public function expression(string $expression, array $parameters = null) : self;
    public function isNull(string $identifier) : self;
    public function isNotNull(string $identifier) : self;
    public function in(string $identifier, array $valueSet = []) : self;
    public function notIn(string $identifier, array $valueSet = []) : self;
    public function between(
        string $identifier,
        int|float|string $minValue,
        int|float|string $maxValue
    ) : self;
    public function notBetween(
        string $identifier,
        int|float|string $minValue,
        int|float|string $maxValue
    ) : self;
    public function predicate(PredicateInterface $predicate) : self;

    // Inherited From PredicateSet

    public function addPredicate(PredicateInterface $predicate, $combination = null) : self;
    public function getPredicates() PredicateInterface[];
    public function orPredicate(PredicateInterface $predicate) : self;
    public function andPredicate(PredicateInterface $predicate) : self;
    public function getExpressionData() : array;
    public function count() : int;
}

Each method in the API will produce a corresponding Predicate object of a similarly named type, as described below.

equalTo(), lessThan(), greaterThan(), lessThanOrEqualTo(), greaterThanOrEqualTo()

$where->equalTo('id', 5);

// The above is equivalent to:
$where->addPredicate(
    new Predicate\Operator($left, Operator::OPERATOR_EQUAL_TO, $right, $leftType, $rightType)
);

Operators use the following API:

class Operator implements PredicateInterface
{
    const OPERATOR_EQUAL_TO                  = '=';
    const OP_EQ                              = '=';
    const OPERATOR_NOT_EQUAL_TO              = '!=';
    const OP_NE                              = '!=';
    const OPERATOR_LESS_THAN                 = '<';
    const OP_LT                              = '<';
    const OPERATOR_LESS_THAN_OR_EQUAL_TO     = '<=';
    const OP_LTE                             = '<=';
    const OPERATOR_GREATER_THAN              = '>';
    const OP_GT                              = '>';
    const OPERATOR_GREATER_THAN_OR_EQUAL_TO  = '>=';
    const OP_GTE                             = '>=';

    public function __construct(
        int|float|bool|string $left = null,
        string $operator = self::OPERATOR_EQUAL_TO,
        int|float|bool|string $right = null,
        string $leftType = self::TYPE_IDENTIFIER,
        string $rightType = self::TYPE_VALUE
    );
    public function setLeft(int|float|bool|string $left);
    public function getLeft() : int|float|bool|string;
    public function setLeftType(string $type) : self;
    public function getLeftType() : string;
    public function setOperator(string $operator);
    public function getOperator() : string;
    public function setRight(int|float|bool|string $value) : self;
    public function getRight() : int|float|bool|string;
    public function setRightType(string $type) : self;
    public function getRightType() : string;
    public function getExpressionData() : array;
}

like($identifier, $like), notLike($identifier, $notLike)

$where->like($identifier, $like):

// The above is equivalent to:
$where->addPredicate(
    new Predicate\Like($identifier, $like)
);

The following is the Like API:

class Like implements PredicateInterface
{
    public function __construct(string $identifier = null, string $like = null);
    public function setIdentifier(string $identifier) : self;
    public function getIdentifier() : string;
    public function setLike(string $like) : self;
    public function getLike() : string;
}

literal($literal)

$where->literal($literal);

// The above is equivalent to:
$where->addPredicate(
    new Predicate\Literal($literal)
);

The following is the Literal API:

class Literal implements ExpressionInterface, PredicateInterface
{
    const PLACEHOLDER = '?';
    public function __construct(string $literal = '');
    public function setLiteral(string $literal) : self;
    public function getLiteral() : string;
}

expression($expression, $parameter)

$where->expression($expression, $parameter);

// The above is equivalent to:
$where->addPredicate(
    new Predicate\Expression($expression, $parameter)
);

The following is the Expression API:

class Expression implements ExpressionInterface, PredicateInterface
{
    const PLACEHOLDER = '?';

    public function __construct(
        string $expression = null,
        int|float|bool|string|array $valueParameter = null
        /* [, $valueParameter, ...  ] */
    );
    public function setExpression(string $expression) : self;
    public function getExpression() : string;
    public function setParameters(int|float|bool|string|array $parameters) : self;
    public function getParameters() : array;
}

isNull($identifier)

$where->isNull($identifier);

// The above is equivalent to:
$where->addPredicate(
    new Predicate\IsNull($identifier)
);

The following is the IsNull API:

class IsNull implements PredicateInterface
{
    public function __construct(string $identifier = null);
    public function setIdentifier(string $identifier) : self;
    public function getIdentifier() : string;
}

isNotNull($identifier)

$where->isNotNull($identifier);

// The above is equivalent to:
$where->addPredicate(
    new Predicate\IsNotNull($identifier)
);

The following is the IsNotNull API:

class IsNotNull implements PredicateInterface
{
    public function __construct(string $identifier = null);
    public function setIdentifier(string $identifier) : self;
    public function getIdentifier() : string;
}

in($identifier, $valueSet), notIn($identifier, $valueSet)

$where->in($identifier, $valueSet);

// The above is equivalent to:
$where->addPredicate(
    new Predicate\In($identifier, $valueSet)
);

The following is the In API:

class In implements PredicateInterface
{
    public function __construct(
        string|array $identifier = null,
        array|Select $valueSet = null
    );
    public function setIdentifier(string|array $identifier) : self;
    public function getIdentifier() : string|array;
    public function setValueSet(array|Select $valueSet) : self;
    public function getValueSet() : array|Select;
}

between($identifier, $minValue, $maxValue), notBetween($identifier, $minValue, $maxValue)

$where->between($identifier, $minValue, $maxValue);

// The above is equivalent to:
$where->addPredicate(
    new Predicate\Between($identifier, $minValue, $maxValue)
);

The following is the Between API:

class Between implements PredicateInterface
{
    public function __construct(
        string $identifier = null,
        int|float|string $minValue = null,
        int|float|string $maxValue = null
    );
    public function setIdentifier(string $identifier) : self;
    public function getIdentifier() : string;
    public function setMinValue(int|float|string $minValue) : self;
    public function getMinValue() : int|float|string;
    public function setMaxValue(int|float|string $maxValue) : self;
    public function getMaxValue() : int|float|string;
    public function setSpecification(string $specification);
}