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Inject database name in queries dynamically #262

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14b8820
Inject database name in queries dynamically
JanJakes Oct 6, 2025
b8e24f4
Inject database name in SELECT wildcards dynamically
JanJakes Oct 13, 2025
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105 changes: 105 additions & 0 deletions tests/WP_SQLite_Driver_Tests.php
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Original file line number Diff line number Diff line change
Expand Up @@ -9244,4 +9244,109 @@ public function testCheckConstraintNotEnforced(): void {
$result[0]->{'Create Table'}
);
}

public function testDynamicDatabaseName(): void {
// Create a setter for the private property "$db_name".
$set_db_name = Closure::bind(
function ( $name ) {
$this->main_db_name = $name;
},
$this->engine,
WP_SQLite_Driver::class
);

// Default database name.
$result = $this->assertQuery( 'SELECT schema_name FROM information_schema.schemata ORDER BY schema_name' );
$this->assertEquals(
array(
(object) array( 'SCHEMA_NAME' => 'information_schema' ),
(object) array( 'SCHEMA_NAME' => 'wp' ),
),
$result
);

// Change the database name.
$set_db_name( 'wp_test_new' );
$result = $this->assertQuery( 'SELECT schema_name FROM information_schema.schemata ORDER BY schema_name' );
$this->assertEquals(
array(
(object) array( 'SCHEMA_NAME' => 'information_schema' ),
(object) array( 'SCHEMA_NAME' => 'wp_test_new' ),
),
$result
);
}

public function testDynamicDatabaseNameComplexScenario(): void {
// Create a setter for the private property "$db_name".
$set_db_name = Closure::bind(
function ( $name ) {
$this->main_db_name = $name;
},
$this->engine,
WP_SQLite_Driver::class
);

$this->assertQuery( 'CREATE TABLE t (id INT, db_name TEXT)' );
$this->assertQuery( 'INSERT INTO t (id, db_name) VALUES (1, "wp")' );
$this->assertQuery( 'INSERT INTO t (id, db_name) VALUES (2, "wp_test_new")' );
$this->assertQuery( 'INSERT INTO t (id, db_name) VALUES (3, "other")' );

$set_db_name( 'wp_test_new' );

$result = $this->assertQuery(
"SELECT sq.id, sq.table_schema, sq.table_name, sq.column_name
FROM (
SELECT * FROM information_schema.columns ist
JOIN t ON t.db_name = CONCAT(COALESCE(ist.table_schema, 'default'), '')
WHERE ist.table_name = 't'
) sq
ORDER BY ordinal_position"
);
$this->assertEquals(
array(
(object) array(
'id' => '2',
'TABLE_SCHEMA' => 'wp_test_new',
'TABLE_NAME' => 't',
'COLUMN_NAME' => 'id',
),
(object) array(
'id' => '2',
'TABLE_SCHEMA' => 'wp_test_new',
'TABLE_NAME' => 't',
'COLUMN_NAME' => 'db_name',
),
),
$result
);
}

public function testDynamicDatabaseNameWithWildcards(): void {
// Create a setter for the private property "$db_name".
$set_db_name = Closure::bind(
function ( $name ) {
$this->main_db_name = $name;
},
$this->engine,
WP_SQLite_Driver::class
);

// Default database name.
$result = $this->assertQuery(
'SELECT * FROM information_schema.schemata s'
);
$this->assertEquals( 'information_schema', $result[0]->SCHEMA_NAME );
$this->assertEquals( 'wp', $result[1]->SCHEMA_NAME );

// Default database name.
$result = $this->assertQuery(
'SELECT s.*
FROM information_schema.schemata s
LEFT JOIN information_schema.tables t ON t.table_schema = s.schema_name
ORDER BY s.schema_name'
);
$this->assertEquals( 'information_schema', $result[0]->SCHEMA_NAME );
$this->assertEquals( 'wp', $result[1]->SCHEMA_NAME );
}
}
241 changes: 239 additions & 2 deletions wp-includes/sqlite-ast/class-wp-sqlite-driver.php
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Original file line number Diff line number Diff line change
Expand Up @@ -3416,7 +3416,16 @@ private function translate_qualified_identifier(

// Object child name (column, index, etc.).
if ( null !== $child_node ) {
$parts[] = $this->translate( $child_node );
$translated = $this->translate( $child_node );
$name = $this->unquote_sqlite_identifier( $translated );
$parts[] = $translated;

// When targeting a database name column from the information schema,
// we need to inject the configured database name.
if ( $this->is_information_schema_db_column( $name ) ) {
$fully_qualified_column = implode( '.', $parts );
return $this->inject_configured_database_name( $fully_qualified_column );
}
}

return implode( '.', $parts );
Expand Down Expand Up @@ -3506,9 +3515,55 @@ private function translate_query_expression( WP_Parser_Node $node ): string {
* @return string|null
*/
private function translate_query_specification( WP_Parser_Node $node ): string {
$from = $node->get_first_child_node( 'fromClause' );
$group_by = $node->get_first_child_node( 'groupByClause' );
$having = $node->get_first_child_node( 'havingClause' );

/*
* Check if the query may possibly read from an information schema table
* using a "*" wildcard, such as "SELECT *", "SELECT t.*", and similar.
* If that's the case, we'll need to expand the wildcard to a list of
* column names and inject the configured database name dynamically.
*/
if ( $from && $from->has_child_node( 'tableReferenceList' ) ) {
$select_item_list = $node->get_first_child_node( 'selectItemList' );
$table_reference_list = $from->get_first_child_node( 'tableReferenceList' );

// Check if the query contains any wildcards.
$has_wildcard = $select_item_list->has_child_token( WP_MySQL_Lexer::MULT_OPERATOR );
if ( ! $has_wildcard ) {
foreach ( $select_item_list->get_child_nodes() as $select_item ) {
if ( $select_item->has_child_node( 'tableWild' ) ) {
$has_wildcard = true;
break;
}
}
}

if ( $has_wildcard ) {
$table_refs = $table_reference_list->get_descendant_nodes( 'tableRef' );

// Check if the query may reference any information schema tables.
// This check is approximate, as it also descends into subqueries.
$references_information_schema = false;
foreach ( $table_refs as $table_ref ) {
$references_information_schema = str_starts_with(
strtolower( $this->translate( $table_ref ) ),
self::RESERVED_PREFIX . 'mysql_information_schema_'
);
if ( $references_information_schema ) {
break;
}
}

// We have both wildcards and information schema tables.
// Let's expand the wildcards to a list of columns.
if ( $references_information_schema ) {
return $this->translate_query_specification_with_information_schema_wildcards( $node );
}
}
}

/*
* When the GROUP BY or HAVING clause is present, we need to disambiguate
* the items to ensure they don't cause an "ambiguous column name" error.
Expand Down Expand Up @@ -3583,6 +3638,83 @@ private function translate_query_specification( WP_Parser_Node $node ): string {
return $this->translate_sequence( $node->get_children() );
}

/**
* Translate a query specification with information schema wildcards to SQLite.
*
* When a SELECT item contains wildcards, such as "SELECT *" or "SELECT t.*",
* and the query references an information schema table, we need to expand the
* wildcards to a list of columns and inject the configured database name.
*
* @param WP_Parser_Node $node The "querySpecification" AST node.
* @return string The translated value.
*/
private function translate_query_specification_with_information_schema_wildcards( WP_Parser_Node $node ): string {
$select_item_list = $node->get_first_child_node( 'selectItemList' );
$from = $node->get_first_child_node( 'fromClause' );
$table_reference_list = $from->get_first_child_node( 'tableReferenceList' );

// Collect all tables used in the query.
$table_alias_map = $this->create_table_reference_map( $table_reference_list );

// Translate the SELECT item list, expanding wildcards that are targeting
// the information schema tables, and replacing the database name with
// the configured database name.
$transformed_list = array();
foreach ( $select_item_list->get_children() as $select_item ) {
if ( $select_item instanceof WP_MySQL_Token ) {
// For a global wildcard ("SELECT *"), we need to expand all tables.
if ( WP_MySQL_Lexer::MULT_OPERATOR === $select_item->id ) {
foreach ( $table_alias_map as $table_alias => $table_data ) {
$transformed_list[] = $this->expand_wildcard( $table_data['table_name'], $table_alias );
}
}
} elseif ( $select_item->has_child_node( 'tableWild' ) ) {
// For a table wildcard ("SELECT t.*"), we expand the given table.
$table_wild = $select_item->get_first_child_node( 'tableWild' );
$identifiers = $table_wild->get_child_nodes( 'identifier' );

// Do not expand the wildcard if the identifier contains a database
// name and targets a different database than "information_schema".
if (
2 === count( $identifiers )
&& '`information_schema`' !== strtolower( $this->translate( $identifiers[0] ) )
) {
$transformed_list[] = $this->translate( $select_item );
continue;
}

// Do not expand the wildcard if the identifier has no database
// name and the current database is not "information_schema".
if (
1 === count( $identifiers )
&& 'information_schema' !== $this->db_name
) {
$transformed_list[] = $this->translate( $select_item );
continue;
}

// Expand the wildcard.
$last_identifier = end( $identifiers );
$alias = $this->unquote_sqlite_identifier( $this->translate( $last_identifier ) );
$table_name = $table_alias_map[ $alias ]['table_name'];
$transformed_list[] = $this->expand_wildcard( $table_name, $alias );
} else {
$transformed_list[] = $this->translate( $select_item );
}
}

// Translate node children, replacing the SELECT list with the transformed one.
$parts = array();
foreach ( $node->get_children() as $child ) {
if ( $child instanceof WP_Parser_Node && 'selectItemList' === $child->rule_name ) {
$parts[] = implode( ', ', $transformed_list );
} else {
$parts[] = $this->translate( $child );
}
}
return implode( ' ', $parts );
}

/**
* Translate a MySQL simple expression to SQLite.
*
Expand Down Expand Up @@ -3916,7 +4048,16 @@ public function translate_select_item( WP_Parser_Node $node ): string {
$column_ref = $node->get_first_descendant_node( 'columnRef' );
$is_column_ref = $column_ref && $item === $this->translate( $column_ref );
if ( $is_column_ref ) {
return $item;
$translated = $this->translate( $column_ref );

// When targeting a database name column from the information schema,
// we need to inject the configured database name and add an alias.
$identifiers = $column_ref->get_descendant_nodes( 'identifier' );
$column_name = $this->unquote_sqlite_identifier( $this->translate( end( $identifiers ) ) );
if ( $this->is_information_schema_db_column( $column_name ) ) {
return sprintf( '%s AS %s', $translated, strtoupper( $column_name ) );
}
return $translated;
}

/*
Expand All @@ -3939,6 +4080,102 @@ public function translate_select_item( WP_Parser_Node $node ): string {
return sprintf( '%s AS %s', $item, $alias );
}

/**
* Check if a column name appears to target an information schema column that
* references the database name ("SCHEMA_NAME", "TABLE_SCHEMA", etc.).
*
* TODO: Fully resolve the column references to ensure that they are really
* referencing the information schema tables.
*
* @param string $column_name The name of the column to check.
* @return bool True if the column is an information schema
* database name column, false otherwise.
*/
private function is_information_schema_db_column( string $column_name ): bool {
static $information_schema_columns = array(
'SCHEMA_NAME' => true,
'TABLE_SCHEMA' => true,
'VIEW_SCHEMA' => true,
'INDEX_SCHEMA' => true,
'CONSTRAINT_SCHEMA' => true,
'UNIQUE_CONSTRAINT_SCHEMA' => true,
'REFERENCED_TABLE_SCHEMA' => true,
'TRIGGER_SCHEMA' => true,
);
return isset( $information_schema_columns[ strtoupper( $column_name ) ] );
}

/**
* Translate a name targeting an information schema database name column
* to an expression that injects the configured database name value.
*
* For example, a reference like "`t`.`table_schema`" will be translated to:
*
* IIF(`t`.`table_schema` = 'information_schema', `t`.`table_schema`, 'database_name')
*
* @param string $column_name The name of the column to translate.
* @return string The translated value.
*/
private function inject_configured_database_name( string $column_name ): string {
return sprintf(
"IIF(%s = 'information_schema', %s, %s)",
$column_name,
$column_name,
$this->connection->quote( $this->main_db_name ),
);
}

/**
* Expand a SELECT wildcard to a list of columns.
*
* This method expands wildcards such as "SELECT *", "SELECT t.*", and similar,
* to an explicit list of all columns in the table. When the wildcard targets
* an information schema table, the configured database name will be injected.
*
* For example, the following query:
*
* SELECT * FROM information_schema.tables t
*
* Will be expanded to:
*
* SELECT t.TABLE_CATALOG, 'database_name' AS TABLE_SCHEMA, t.TABLE_NAME, ...
* FROM information_schema.tables t
*
* @param string $table_name The name of the table to expand the wildcard for.
* @param string $table_alias The alias of the table to expand the wildcard for.
* @return string The expanded and translated list of columns.
*/
private function expand_wildcard( string $table_name, string $table_alias ): string {
// We need to fetch the SQLite column information, because the information
// schema tables don't contain records for the information schema itself.
$result = $this->execute_sqlite_query(
'SELECT name FROM pragma_table_info(?)',
array( $table_name )
);

// List all columns in the table, replacing columns targeting database
// name columns with the configured database name.
$columns = $result->fetchAll( PDO::FETCH_COLUMN );
$expanded_list = array();
foreach ( $columns as $column ) {
$fully_qualified_column = sprintf(
'%s.%s',
$this->quote_sqlite_identifier( $table_alias ),
$this->quote_sqlite_identifier( $column )
);
if ( $this->is_information_schema_db_column( $column ) ) {
$expanded_list[] = sprintf(
'%s AS %s',
$this->inject_configured_database_name( $fully_qualified_column ),
strtoupper( $column ),
);
} else {
$expanded_list[] = $fully_qualified_column;
}
}
return implode( ', ', $expanded_list );
}

/**
* Recreate an existing table using data in the information schema.
*
Expand Down
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