Meta_Query comparar explicação do operador

Oprimeirotrabalho como vocêesperaria:

 =   equals
!=  does not equal
>   greater than
>=  greater than or equal to
<   less than
<=  less than or equal to
 

como e não como

LIKEe NOT LIKE são operadores SQL quepermitem adicionar símbolos de cartões selvagens,para que vocêpossater umameta consulta que separece comesta:

 array( 
    'key' => 'name', 
    'value' => 'Pat', 
    'compare' => 'LIKE'
)
 

Isso retornariatodas aspostagensem que o "nome" valormetatem a string "Pat". Neste caso,"Pat" "Patricia"e "Patrick" seriamtodos retornados de voltapara você. Há umtutorialnão wordpress Explicação aqui .

Adicionando o caractere curinga %não énecessário,porque é adicionadoporpadrão como @Herb disseno seu abaixo Resposta . Assim: $meta_value = '%' . like_escape( $meta_value ) . '%'; - consulte fonte .

em e nãoem

INe NOT IN selecione qualquer correspondência queestejam (ounão)namatriz dada. Então vocêpoderiafazer algo assim:

 array(
    'key'     => 'color', 
    'value'   => array('red', 'green', 'blue') 
    'compare' => 'IN'
)
 

e obterátodas aspostagens quetêm a cor definidapara vermelho,verde ou azul. Usando 'nãoem' recebe oinverso,quaisquerposts quetêm um valor definidopara qualquer outra coisa do queno array.

O SQLgeradoparaisso seria algo assim:

 array( 
    'key' => 'price', 
    'value' => array(20,30) 
    'compare' => 'BETWEEN'
)
 

 array( 
    'key' => 'price', 
    'compare' => 'NOT EXISTS'
)
 

The first several work as you would expect:

=   equals
!=  does not equal
>   greater than
>=  greater than or equal to
<   less than
<=  less than or equal to

LIKE and NOT LIKE

LIKE and NOT LIKE are SQL operators that let you add in wild-card symbols, so you could have a meta query that looks like this:

array( 
    'key' => 'name', 
    'value' => 'Pat', 
    'compare' => 'LIKE'
)

This would return all posts where the meta value "name" has the string "Pat". In this case, "Pat" "Patricia" and "Patrick" would all be returned back to you. There's a non-WordPress tutorial explanation here.

Adding the wildcard character % isn't necessary, because it gets added by default like @Herb said in his below answer. Like this: $meta_value = '%' . like_escape( $meta_value ) . '%'; - see source.

IN and NOT IN

IN and NOT IN select any matches that are in (or not in) the given array. So you could do something like this:

array(
    'key'     => 'color', 
    'value'   => array('red', 'green', 'blue') 
    'compare' => 'IN'
)

and it would get all posts that have the color set to either red, green, or blue. Using 'NOT IN' gets the reverse, any posts that have a value set to anything else than what's in the array.

The generated SQL for this would look something like this:

SELECT * FROM posts_meta WHERE value IN ("red", "green", "blue") 

BETWEEN and NOT BETWEEN

BETWEEN and NOT BETWEEN allow you to define a range of values that could be correct, and require you to give two values in an array in your meta_query:

array( 
    'key' => 'price', 
    'value' => array(20,30) 
    'compare' => 'BETWEEN'
)

This will get you all posts where the price is between 20 and 30. This person digs into an example with dates.

NOT EXISTS

NOT EXISTS is just like what it sounds - the meta value isn't set or is set to a null value. All you need for that query is the key and comparison operator:

array( 
    'key' => 'price', 
    'compare' => 'NOT EXISTS'
)

This person needed to query non-existent meta values, and needed them to play nice with others.

Hope this helps!

Observe que ao usar um valor META_COMPARE de 'Like',o WordPressenvolve automaticamente o caractere curinga (%) ao redor da string Meta_Value.Portanto,oexemplo "Pat%"podenão conseguir retornar quaisquer resultados.

Note that when using a meta_compare value of 'LIKE', WordPress automatically wraps the wildcard character ( % ) around the meta_value string. So the 'Pat%' example could fail to return any results.