Question

I have sql error null value in column “kladr_full_name” violates not-null constraint.

Table in database to wich request is performed:

СREATE TABLE kladr.kladr_name
(
  kladr_code character varying(255) NOT NULL,
  kladr_city_name character varying(121),
  kladr_full_name character varying(487) NOT NULL,
  kladr_index character varying(6),
  kladr_name character varying(100) NOT NULL,
  kladr_naspunkt_name character varying(121),
  kladr_rayon_name character varying(121),
  kladr_region_name character varying(121),
  kladr_socr character varying(20),
  CONSTRAINT kladr_name_pkey PRIMARY KEY (kladr_code )
)
WITH (
  OIDS=FALSE
);
ALTER TABLE kladr.kladr_name
  OWNER TO postgres;

Request to db:

    INSERT INTO kladr.kladr_name 
            (kladr_code, 
             kladr_name, 
             kladr_socr, 
             kladr_index, 
             kladr_region_name, 
             kladr_rayon_name, 
             kladr_city_name, 
             kladr_naspunkt_name, 
             kladr_full_name) 
SELECT kladr_code, 
       Upper(kladr_name)                 kladr_name, 
       kladr_socr, 
       kladr_index, 
       (SELECT k1.kladr_socr 
               ||' ' 
               ||k1.kladr_name 
        FROM   kladr.kladr_tmp k1 
        WHERE  k1.kladr_region = k.kladr_region 
               AND k1.kladr_rayon = '000' 
               AND k1.kladr_city = '000' 
               AND k1.kladr_nas_punkt = '000' 
               AND k1.kladr_mod = '00' 
               AND k1.kladr_status = '0')kladr_region_name, 
       (SELECT k1.kladr_socr 
               ||' ' 
               ||k1.kladr_name 
        FROM   kladr.kladr_tmp k1 
        WHERE  k1.kladr_region = k.kladr_region 
               AND k1.kladr_rayon = k.kladr_rayon 
               AND k1.kladr_rayon <> '000' 
               AND k1.kladr_city = '000' 
               AND k1.kladr_nas_punkt = '000' 
               AND k1.kladr_name = '00') kladr_rayon_name, 
       (SELECT k1.kladr_socr 
               ||' ' 
               ||k1.kladr_name 
        FROM   kladr.kladr_tmp k1 
        WHERE  k1.kladr_region = k.kladr_region 
               AND k1.kladr_rayon = k.kladr_rayon 
               AND k1.kladr_city = k.kladr_city 
               AND k1.kladr_city <> '000' 
               AND k1.kladr_nas_punkt = '000' 
               AND k1.kladr_mod = '00')  kladr_city_name, 
       (SELECT k1.kladr_socr 
               ||' ' 
               ||k1.kladr_name 
        FROM   kladr.kladr_tmp k1 
        WHERE  k1.kladr_region = k.kladr_region 
               AND k1.kladr_rayon = k.kladr_rayon 
               AND k1.kladr_city = k.kladr_city 
               AND k1.kladr_nas_punkt = k.kladr_nas_punkt 
               AND k1.kladr_nas_punkt <> '000' 
               AND k1.kladr_mod = '00')  kladr_naspunkt_name, 
       (SELECT k1.kladr_socr 
               ||' ' 
               ||k1.kladr_name 
        FROM   kladr.kladr_tmp k1 
        WHERE  k1.kladr_region = k.kladr_region 
               AND k1.kladr_rayon = '000' 
               AND k1.kladr_city = '000' 
               AND k1.kladr_nas_punkt = '000' 
               AND k1.kladr_mod = '00' 
               AND k1.kladr_status = '0') 
       ||' ' 
       ||(SELECT k1.kladr_socr 
                 ||' ' 
                 ||k1.kladr_name 
          FROM   kladr.kladr_tmp k1 
          WHERE  k1.kladr_region = k.kladr_region 
                 AND k1.kladr_rayon = k.kladr_rayon 
                 AND k1.kladr_rayon <> '000' 
                 AND k1.kladr_city = '000' 
                 AND k1.kladr_nas_punkt = '000' 
                 AND k1.kladr_mod = '00') 
       ||' ' 
       ||(SELECT k1.kladr_socr 
                 ||' ' 
                 ||k1.kladr_name 
          FROM   kladr.kladr_tmp k1 
          WHERE  k1.kladr_region = k.kladr_region 
                 AND k1.kladr_rayon = k.kladr_rayon 
                 AND k1.kladr_city = k.kladr_city 
                 AND k1.kladr_city <> '000' 
                 AND k1.kladr_nas_punkt = '000' 
                 AND k1.kladr_mod = '00') 
       ||' ' 
       ||(SELECT k1.kladr_socr 
                 ||' ' 
                 ||k1.kladr_name 
          FROM   kladr.kladr_tmp k1 
          WHERE  k1.kladr_region = k.kladr_region 
                 AND k1.kladr_rayon = k.kladr_rayon 
                 AND k1.kladr_city = k.kladr_city 
                 AND k1.kladr_nas_punkt = k.kladr_nas_punkt 
                 AND k1.kladr_nas_punkt <> '000' 
                 AND k1.kladr_mod = '00')kladr_full_name 
FROM   kladr.kladr_tmp k 
WHERE  k.kladr_mod = '00' 

DB postgreSql. jpa prov hibernate. What could be the reason of this?

Question now is how to modify this query to work in postgres(before it was working in oracle db) if some subquerys returns null?

Answer 1

In PostgreSQL, an expression of the form a || b will evaluate to NULL if either of its arguments is NULL. So, your INSERT statement will try to insert NULL into kladr_full_name if any of those subqueries fails to find a record. You need to try each of those subqueries separately, and see which one is not giving you a record (or is giving you a record with NULL).

---

Edited to add in response to OP comment: In Oracle, there’s no concept of zero-length strings, because they’re converted to NULL (so, for example, '' = '' is not true, whereas '' IS NULL is). Usually the conversion is one-way — LENGTH('') IS NULL — but in the case of the || operator, it converts NULL back to a zero-length string, such that 'ab' || NULL || 'cd' is 'abcd'. PostgreSQL doesn’t do this conversion automatically, because it does distinguish '' from NULL, but you can either:

• perform this conversion explicitly by using the COALESCE function (documented in §9.17 “Conditional Expressions” of the PostgreSQL 9.2 Manual): COALESCE(NULL, '') evaluates to ''; or
• use the CONCAT function (documented in §9.4 “String Functions and Operators” of the PostgreSQL 9.2 Manual) instead of the || operator. The CONCAT function simply skips over any NULL arguments, so CONCAT('ab', NULL, 'cd') evaluates to 'abcd'. However, this function is only available starting in PostgreSQL 9.x, so if you’re using PostgreSQL 8.x or older, you’ll need to use the COALESCE approach.