CODEWITHSUNDEEP
mysqlsyntaxquotes
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Reputation: 13

Mysql 3 single quotes in a row

I came across the query below to dynamically convert rows into columns with Mysql. Does anyone know what the the 3 single quotes do before & after the Product_Name field?

  SET @sql = NULL;
   SELECT
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'count(case when Product_Name = ''',
      Product_Name,
      ''' then 1 end) AS ',
      replace(Product_Name, ' ', '')
    )
  ) INTO @sql
from products;

SET @sql = CONCAT('SELECT pt.partner_name, ', @sql, ' from partners pt
left join sales s
  on pt.part_id = s.partner_id
left join products pd
  on s.product_id = pd.prod_id
group by pt.partner_name');

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

Upvotes: 1

Views: 126

Answers (1)

Bill Karwin
Bill Karwin

Reputation: 562270

https://dev.mysql.com/doc/refman/5.7/en/string-literals.html says:

A ' inside a string quoted with ' may be written as ''.

There are lots of examples on that manual page.

Upvotes: 2

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