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Final Class Yiisoft\Db\Expression\Statement\CaseX

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InheritanceYiisoft\Db\Expression\Statement\CaseX
ImplementsYiisoft\Db\Expression\ExpressionInterface

Represents a SQL CASE expression.

A CASE expression allows conditional logic in SQL queries, returning different values based on specified conditions. It can be used to implement complex logic directly in SQL statements.

Example usage:

$case = new CaseX(
    when1: new WhenThen(true, 'result1'),
    when2: new WhenThen(false, 'result2'),
    else: 'default result',
);

This will be generated into a SQL CASE expression like:

CASE
    WHEN TRUE THEN 'result1'
    WHEN FALSE THEN 'result2'
    ELSE 'default result'
END

Example with a specific case value:

$case = new CaseX(
     'column_name',
     when1: new WhenThen('one', 'result1'),
     when2: new WhenThen('two', 'result2'),
     else: 'default result',
);

This will be generated into a SQL CASE expression like:

CASE "column_name"
    WHEN 'one' THEN 'result1'
    WHEN 'two' THEN 'result2'
    ELSE 'default result'
END

Public Properties

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Property Type Description Defined By
$else mixed The result to return if no conditions match in the CASE expression. Yiisoft\Db\Expression\Statement\CaseX
$value mixed Yiisoft\Db\Expression\Statement\CaseX
$valueType string|\Yiisoft\Db\Schema\Column\ColumnInterface Yiisoft\Db\Expression\Statement\CaseX
$whenThen Yiisoft\Db\Expression\Statement\WhenThen[] List of WHEN-THEN conditions and their corresponding results in the CASE expression. Yiisoft\Db\Expression\Statement\CaseX

Public Methods

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Method Description Defined By
__construct() Yiisoft\Db\Expression\Statement\CaseX
hasElse() Returns true if the CASE expression has an ELSE clause, false otherwise. Yiisoft\Db\Expression\Statement\CaseX

Property Details

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$else public property

The result to return if no conditions match in the CASE expression. If not set, the CASE expression will not have an ELSE clause.

public mixed $else = null
$value public property
public mixed $value = null
$valueType public property
public string|\Yiisoft\Db\Schema\Column\ColumnInterface $valueType = ''
$whenThen public property

List of WHEN-THEN conditions and their corresponding results in the CASE expression.

public Yiisoft\Db\Expression\Statement\WhenThen[] $whenThen = null

Method Details

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__construct() public method

public mixed __construct ( mixed $value = null, Yiisoft\Db\Schema\Column\ColumnInterface|string $valueType = '', mixed|Yiisoft\Db\Expression\Statement\WhenThen $args )
$value mixed

Comparison condition in the CASE expression:

  • string is treated as a table column name which will be quoted before usage in the SQL statement;
  • array is treated as a condition to check, see {@see \Yiisoft\Db\Query\QueryInterface::where()};
  • other values will be converted to their string representation using {@see \Yiisoft\Db\Expression\Statement\QueryBuilderInterface::buildValue()}. If not provided, the CASE expression will be a WHEN-THEN structure without a specific case value.
$valueType Yiisoft\Db\Schema\Column\ColumnInterface|string

Optional data type of the CASE expression which can be used in some DBMS to specify the expected type (for example, in PostgreSQL).
$args mixed|Yiisoft\Db\Expression\Statement\WhenThen

List of WHEN-THEN conditions and their corresponding results represented as {@see \Yiisoft\Db\Expression\Statement\WhenThen} instances or ELSE value in the CASE expression. String ELSE value will be quoted before usage in the SQL statement.

 

                public function __construct(
    public readonly mixed $value = null,
    public readonly string|ColumnInterface $valueType = '',
    mixed ...$args,
) {
    $whenThen = [];
    foreach ($args as $arg) {
        if ($arg instanceof WhenThen) {
            $whenThen[] = $arg;
        } elseif ($this->hasElse()) {
            throw new InvalidArgumentException('`CASE` expression can have only one `ELSE` value.');
        } else {
            $this->else = $arg;
        }
    }
    if (empty($whenThen)) {
        throw new InvalidArgumentException('`CASE` expression must have at least one `WHEN-THEN` clause.');
    }
    $this->whenThen = $whenThen;
}
hasElse() public method

Returns true if the CASE expression has an ELSE clause, false otherwise.

public boolean hasElse ( )

                public function hasElse(): bool
{
    return array_key_exists('else', get_object_vars($this));
}