wpdb::get_var( string|null $query = null, int $x = 0, int $y = 0 ): string|null
- Since
- 0.71
- Source
wp-includes/class-wpdb.php:3027
Description
Executes a SQL query and returns the value from the SQL result.
If the SQL result contains more than one column and/or more than one row, the value in the column and row specified is returned. If $query is null, the value in the specified column and row from the previous SQL result is returned.
Compatibility
- WordPress
- since 0.71
- PHP
- 7.4–8.6-dev
- 6.7.7
- 6.8.8
- 6.9.7
- 7.0.4
- 7.1.0
Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.
Parameters
$querystring|nulloptional- SQL query. Defaults to null, use the result from the previous query.Default:
null $xintoptional- Column of value to return. Indexed from 0. Default 0.Default:
0 $yintoptional- Row of value to return. Indexed from 0. Default 0.Default:
0
Return value
string|null- Database query result (as string), or null on failure.
Performance profile
How much work a call to wpdb::get_var() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.
- Cost class
- Heavy
- Scaling
- Constant
- Instructions
- 19–43
- Plugin surface
- None
- Called by
- 1
Reaches the database via wpdb::get_var().
No loop in the body: the same number of instructions runs whatever you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 44.
Nothing here hands control to plugin code.
1 place in core call this, so the cost is paid more often than your own code shows.
What it touches
- sqldatabase query
wpdb::get_var()this function does it
What one call costs · 6 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost wpdb::get_var() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
empty($y) | 19–23 | none |
empty($y) | 24–28 | ->query() |
!empty($y) | 28–32 | get_object_vars(), array_values() |
empty($y) | 28–34 | ->check_safe_collation(), ->query() |
!empty($y) | 33–37 | ->query(), get_object_vars(), array_values() |
!empty($y) | 37–43 | ->check_safe_collation(), ->query(), get_object_vars(), array_values() |
Across PHP versions
Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 44 instructions, 19–43 executed per call, 6 branches. The work does not change between versions.
An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.
Uses · 2
- wpdb::check_safe_collation()Checks if the query is accessing a collation considered safe.
- wpdb::query()Performs a database query, using current database connection.
Used by · 1
- wpdb::get_col()Retrieves one column from the database.
Source code
public function get_var( $query = null, $x = 0, $y = 0 ) { $this->func_call = "\$db->get_var(\"$query\", $x, $y)"; if ( $query ) { if ( $this->check_current_query && $this->check_safe_collation( $query ) ) { $this->check_current_query = false; } $this->query( $query ); } // Extract var out of cached results based on x,y vals. if ( ! empty( $this->last_result[ $y ] ) ) { $values = array_values( get_object_vars( $this->last_result[ $y ] ) ); } // If there is a value return it, else return null. return ( isset( $values[ $x ] ) && '' !== $values[ $x ] ) ? $values[ $x ] : null; }Changelog
Introduced in 0.71. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
About this page
- Parsed data
- Generated from the wordpress-develop 7.0.4 tag, from
src/wp-includes/class-wpdb.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it. - Corrections
- Something wrong on this page? Report it and it gets fixed in the next regeneration.