元查询比较运算符说明

您期望的前几项工作:

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

喜欢和不喜欢

LIKE和NOT LIKE是SQL运算符,可用于添加通配符,因此您可以使用如下所示的元查询:

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

这将返回元值"name"具有字符串" Pat"的所有帖子.在这种情况下," Pat"," Patricia"和" Patrick"将全部退还给您.在此处.

不需要添加通配符%,因为默认情况下会添加通配符,如@Herb在其下面的答案.像这样:$meta_value = '%' . like_escape( $meta_value ) . '%';-请参见来源.

IN 和 NOT IN

IN和NOT IN选择在给定数组中(或不在给定数组中)的任何匹配项.因此,您可以执行以下操作:

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

,它将获得所有颜色设置为红色,绿色或蓝色的帖子.使用" NOT IN"得到相反的结果,即任何将值设置为数组中值以外的值的帖子.

为此生成的SQL如下所示:

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

更好和不喜欢

BETWEEN和NOT BETWEEN允许您定义可能正确的值范围,并要求您在meta_query的数组中提供两个值:

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

这将为您提供价格在20到30之间的所有帖子.这个人深入研究一个带有日期的示例.

不存在

NOT EXISTS听起来很像-未设置元值或将其设置为空值.该查询所需的全部就是键和比较运算符:

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

此人需要查询非存在的元值,并需要它们与他人一起玩耍.

希望这会有所帮助！

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!

请注意,当使用meta_compare值'LIKE'时,WordPress会自动在meta_value字符串周围包裹通配符(％).因此," Pat％"示例可能无法返回任何结果.

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.