Question

PostgreSQL 11.1 使用以下sql查询，其中$ 1和$ 2是字符串，$ 3是时间戳，如何重写以下查询，以便$ 3中的空值允许选择每个日期（不仅是空日期）。

   SELECT lastname, firstname, birthdate FROM patients 
           WHERE UPPER(lastname) LIKE UPPER($1)||'%' and UPPER(firstname) LIKE UPPER($2)||'%' AND birthdate::date = $3::date
        UNION
        SELECT lastname, firstname, birthdate FROM appointment_book 
           WHERE UPPER(lastname) LIKE UPPER($1)||'%' and UPPER(firstname) LIKE UPPER($2)||'$' and birthdate::date = $3::date

也就是说，如果$ 3为空，则应减少为：

SELECT lastname, firstname, birthdate FROM patients 
               WHERE UPPER(lastname) LIKE UPPER($1)||'%' and UPPER(firstname) LIKE UPPER($2)||'%' 
            UNION
            SELECT lastname, firstname, birthdate FROM appointment_book 
               WHERE UPPER(lastname) LIKE UPPER($1)||'%' and UPPER(firstname) LIKE UPPER($2)||'$'

Answer 1

未经测试，但我认为您可以使用CASE表达式来处理

SELECT lastname, firstname, birthdate FROM patients p
  WHERE UPPER(p.lastname) LIKE UPPER($1)||'%'
  AND   UPPER(p.firstname) LIKE UPPER($2)||'%'
  AND   (CASE WHEN $3 IS NULL THEN TRUE
         ELSE                      p.birthdate::date = $3::date
         END)
UNION
SELECT lastname, firstname, birthdate FROM appointment_book ab
  WHERE UPPER(ab.lastname) LIKE UPPER($1)||'%'
  AND   UPPER(ab.firstname) LIKE UPPER($2)||'%'
  AND   (CASE WHEN $3 IS NULL THEN TRUE
         ELSE                      ab.birthdate::date = $3::date
         END);

如何在sql查询（PostgreSQL）中管理NULL字符串或日期

1 个答案: