编写Postgresql查询的问题

Question

I am new to Postgresql.I need to write a search query where i have array of values which is to be searched in a column that holds array.How can i search that atleast one value from my search array is present in the column array.

this is my array which is to be searched,

Array
(
[0] => 24
[1] => 25
[2] => 26
)

& my table w_business has a column categories that contains values as:

["23","45","24"]
["11","34"]

ho can i write query for searching in POSTGRESQL?

Answer 1

Your best chance at solving the immediate problem is probably a PHP function that returns part of a well-formatted WHERE clause. But you have a lot more trouble coming up. The very best use of your time right now is in getting that table fixed.

Having said that, let's create a table and some sample rows.

create temp table scratch (
  scratch_id integer primary key,
  categories text
);

insert into scratch values (1, '24, 35, 36'); -- Well-formed match
insert into scratch values (2, '23, 24, 35'); -- Well-formed match
insert into scratch values (3, '33, 34, 24'); -- Well-formed match
insert into scratch values (4, '24,35,36'); -- Ill-formed match; no spaces
insert into scratch values (5, '23,24,36'); -- Ill-formed match; no spaces
insert into scratch values (6, '22,23,24'); -- Ill-formed match; no spaces
insert into scratch values (7, '24 , 35 , 36'); -- Ill-formed match
insert into scratch values (8, '23 , 24 , 35'); -- Ill-formed match
insert into scratch values (9, '23 , 24  '); -- Ill-formed match
insert into scratch values (10, '  24 ,34  '); -- Ill-formed match

insert into scratch values (100, '2424'); -- Well-formed fail
insert into scratch values (101, '1224, 241');-- Well-formed fail

And a PHP function that returns a well-formatted WHERE clause. (Well-formatted as far as SQL is concerned, that is.) This builds a WHERE clause on the fly. ( See this article for why you shouldn't do this.) How well this works depends on how consistent your data is. Since the database designer has thrown type safety to the winds, you'll need some luck here. (Without type safety, you're liable to find values like "24, 25i, wibble" in there.)

function where_clause_for_categories($arr) {
  $categories = [];
  $patterns = array (
               "begin" => '^:val:[, ]', 
               "middle" => '[, ]:val:[, ]', 
               "end" => '[, ]:val:$'
              );
  $full_pattern = "";
  foreach ($arr as $value) {
      foreach ($patterns as $pattern) {
        $full_pattern = str_replace(":val:", $value, $pattern);
        array_push($categories, "categories ~ '" . $full_pattern . "'");
      }
  }
  $where = implode(' or ', $categories);

  if (strlen($where) > 0) {
    $where = '(' . $where . ')';    
  }
  return $where;
}

A quick test . . .

$arr = [24, 25];
echo where_clause_for_categories($arr);
// (categories ~ '^24[, ]' or categories ~ '[, ]24[, ]' or categories ~ '[, ]24$'
 or categories ~ '^25[, ]' or categories ~ '[, ]25[, ]' or categories ~ '[, ]25$')

The outer parens guard against side effects when you combine this with other parts of a WHERE clause.

Assuming you won't pass an empty array to where_clause_for_categories(), you can change the last part of your code to this.

echo $qry="SELECT * FROM w_business WHERE enabled='t' AND " . where_clause_for_categories($arr);