PL/SQL Automatic Constraint Handler(Code)

Question

For those interested...
I created the following database code that automatically does the constraint check/return error message for you.
You could even take this a step further and create your own message repository...
This guy even grabs/checks for foreign key violations:
First part of code builds/returns dictionary data constraints for table that you specify.
It then loads this data into object type.
This object type will be referenced later in the database trigger that you create for table where you want to validate constraints
return DbCons_documents_Array
as
dbdata DbCons_documents_Array := DbCons_documents_Array();
i NUMBER := 1;
begin
FOR cns_rec IN(select child.child_cons_name clchild_cons_name,
child.parent_cons_name clparent_cons_name,
child.child_columns clchild_columns,
parent.parent_cons_name pparent_cons_name,
parent.parent_tname pparent_tname,
child.child_tname clchild_tname,
CONCAT(CONCAT('"',replace(replace(parent.parent_columns,'"',''),'''','')),'"') pparent_columns,
child.parent_cons_type pparent_cons_type
--CONCAT(CONCAT('''',web_form_array(find_web_frm_val).db_col_value),'''');
FROM (
select a.table_name child_tname,
a.constraint_name child_cons_name,
NVL(b.r_constraint_name,a.constraint_name) parent_cons_name,
b.constraint_type parent_cons_type,
max(decode(position, 1, '"'||column_name||'"',NULL)) ||
max(decode(position, 2,', '||'"'||column_name||'"',NULL)) ||
max(decode(position, 3,', '||'"'||column_name||'"',NULL)) ||
max(decode(position, 4,', '||'"'||column_name||'"',NULL)) ||
max(decode(position, 5,', '||'"'||column_name||'"',NULL)) ||
max(decode(position, 6,', '||'"'||column_name||'"',NULL)) ||
max(decode(position, 7,', '||'"'||column_name||'"',NULL)) ||
max(decode(position, 8,', '||'"'||column_name||'"',NULL)) ||
max(decode(position, 9,', '||'"'||column_name||'"',NULL)) ||
max(decode(position,10,', '||'"'||column_name||'"',NULL)) ||
max(decode(position,11,', '||'"'||column_name||'"',NULL)) ||
max(decode(position,12,', '||'"'||column_name||'"',NULL)) ||
max(decode(position,13,', '||'"'||column_name||'"',NULL)) ||
max(decode(position,14,', '||'"'||column_name||'"',NULL)) ||
max(decode(position,15,', '||'"'||column_name||'"',NULL)) ||
max(decode(position,16,', '||'"'||column_name||'"',NULL))
child_columns
from user_cons_columns a, user_constraints b
where a.constraint_name = b.constraint_name
and b.constraint_type IN ( 'U', 'R' )
--and nvl(B.r_constraint_name,B.constraint_name) = A.constraint_name
-- and nvl(a.r_owner,a.owner) = b.owner
group by a.table_name, a.constraint_name, b.r_constraint_name,b.constraint_type ) child,
( select a.constraint_name parent_cons_name,
a.table_name parent_tname,
max(decode(position, 1, '"'||column_name||'"',NULL)) ||
max(decode(position, 2,', '||'"'||column_name||'"',NULL)) ||
max(decode(position, 3,', '||'"'||column_name||'"',NULL)) ||
max(decode(position, 4,', '||'"'||column_name||'"',NULL)) ||
max(decode(position, 5,', '||'"'||column_name||'"',NULL)) ||
max(decode(position, 6,', '||'"'||column_name||'"',NULL)) ||
max(decode(position, 7,', '||'"'||column_name||'"',NULL)) ||
max(decode(position, 8,', '||'"'||column_name||'"',NULL)) ||
max(decode(position, 9,', '||'"'||column_name||'"',NULL)) ||
max(decode(position,10,', '||'"'||column_name||'"',NULL)) ||
max(decode(position,11,', '||'"'||column_name||'"',NULL)) ||
max(decode(position,12,', '||'"'||column_name||'"',NULL)) ||
max(decode(position,13,', '||'"'||column_name||'"',NULL)) ||
max(decode(position,14,', '||'"'||column_name||'"',NULL)) ||
max(decode(position,15,', '||'"'||column_name||'"',NULL)) ||
max(decode(position,16,', '||'"'||column_name||'"',NULL))
parent_columns
from user_cons_columns a, user_constraints b
where a.constraint_name = b.constraint_name
and b.constraint_type in ( 'P', 'U', 'R' )
group by a.table_name, a.constraint_name ) parent
where child.parent_cons_name = parent.parent_cons_name
and child.child_tname = upper('YOUR TABLE NAME HERE')
LOOP
dbdata.extend(i);
dbdata(i) := cdrl5.dbconstraint_documents_rec(cns_rec.pparent_cons_name,cns_rec.clchild_tname,cns_rec.pparent_tname,cns_rec.pparent_columns,cns_rec.pparent_cons_type);
--dbdata(i) := '';
-- dbdata(i) := dbconstraint_rec('test','test','test','test');
--v_sql :=
-- dbdata(i).constraint_name;
i := i+1;
END LOOP;
FOR d IN 1..dbdata.COUNT
LOOP
IF dbdata(d).constraint_name IS NULL
THEN
dbdata.delete(d);
END IF;
END LOOP;
-- dbdata.delete;
return dbdata;
END;
Second part is code that is in trigger of table you are inserting into. Note that you have to store the table name/column name(that make up the constraint)/actual form values into pl/sql table:
DECLARE
v_sql VARCHAR2(32000);
v_literal_value VARCHAR2(100);
v_error_relay VARCHAR2(4000);
v_db_values NUMBER := 1;
v_dup_count NUMBER;
nforeign_key EXCEPTION;
TYPE DupRecordType IS REF CURSOR;
dup_rec_cv DupRecordType;
dbdata DbCons_Documents_Array := DbCons_Documents_Array(cdrl5.dbconstraint_documents_rec(null,null,null,null,null));
TYPE tokenTableType is TABLE of varchar2(4000) -- table for Stringtoken
index by binary_integer;
tokenChar VARCHAR2(4000) := '," ';
tokens tokenTableType;
vCnt integer := 1;
myLine varchar2(4000) := null;
Line varchar2(4000) := null;
vPos integer := 1;
TYPE form_rec IS RECORD
table_name VARCHAR2(100),
db_column VARCHAR2(100),
db_col_value VARCHAR2(1000)
TYPE form_type IS TABLE OF form_rec
INDEX BY binary_integer;
web_form_array form_type;
BEGIN
dbdata.DELETE;
-- IF :new.DOC_ID IS NOT NULL
-- THEN
NOTE: Load the below table(with values specified) for each table constraint
web_form_array(v_db_values).table_name :=
'YOUR TABLE NAME';
web_form_array(v_db_values).db_column :=
'YOUR FIELD NAME';
web_form_array(v_db_values).db_col_value :=
:new.;
v_db_values := v_db_values +1;
FOR cns_rec IN(select *
from TABLE ( cast( documents_cons_dml() as DbCons_documents_Array ))
LOOP
line :=
cns_rec.constraint_where;
v_sql := 'SELECT count(*) FROM '||cns_rec.constraint_column;
IF INSTR(line,',',1,1) <= 0
THEN
FOR find_web_frm_val IN 1..web_form_array.COUNT
LOOP
IF cns_rec.table_name = web_form_array(find_web_frm_val).table_name
AND replace(line,'"','') = web_form_array(find_web_frm_val).db_column
THEN
v_literal_value :=
CONCAT(CONCAT('''',web_form_array(find_web_frm_val).db_col_value),'''');
v_sql := v_sql||' WHERE '||' '||web_form_array(find_web_frm_val).db_column||' = '||v_literal_value;
END IF;
END LOOP;
ELSE
while (vPos <= length(line))
loop
if (length(replace(tokenChar,substr(line, vPos, 1), '')) = length(tokenChar))
then
myLine := myLine || substr(line, vPos, 1);
elsif (myLine is not NULL) then
tokens(vCnt) := myLine;
FOR find_web_frm_val IN 1..v_db_values
LOOP
IF cns_rec.table_name = web_form_array(find_web_frm_val).table_name
AND MYLine = web_form_array(find_web_frm_val).db_column
THEN
v_literal_value :=
CONCAT(CONCAT('''',web_form_array(find_web_frm_val).db_col_value),'''');
END IF;
end loop;
IF vCnt = 1
THEN
v_sql := v_sql||' WHERE '||' '||myLine||' = '||v_literal_value;
ELSE
v_sql := v_sql||' AND '||' '||myLine||' = '||v_literal_value;
END IF;
myLine := null;
vCnt := vCnt + 1;
end if;
vPos := vPos + 1;
end loop;
if (myLine is not NULL) then
tokens(vCnt) := myLine;
end if;
vCnt := 1;
vPos := 1;
END IF;
OPEN dup_rec_cv FOR v_sql;
FETCH dup_rec_cv
INTO v_dup_count;
CLOSE dup_rec_cv;
IF cns_rec.column_position = 'R'
THEN
IF v_dup_count <= 0
THEN
v_error_relay :=
'The form field value for Database Column '||' '||line||' '||' that was entered does not exist';
RAISE nforeign_key;
END IF;
ELSIF cns_rec.column_position = 'U'
THEN
IF v_dup_count > 0
THEN
RAISE DUP_VAL_ON_INDEX;
END IF;
END IF;
-- commit_trans(v_dup_count);
-- INSERT INTO test
-- values(line||' '||INSTR(line,',',1,1));
-- VALUES(cns_rec.constraint_name||' '||cns_rec.table_name||' '||cns_rec.constraint_column||' '||cns_rec.constraint_where);
-- values(v_sql||' '||vPos||' '||length(line));
-- VALUES(web_form_array(i).table_name||' '||CONCAT(CONCAT('''',web_form_array(i).db_col_value),'''')||' '||i);
--commit;
-- i := i+1;
END LOOP;
EXCEPTION
WHEN DUP_VAL_ON_INDEX
THEN
raise_application_error(-20101, 'Attempted to update duplicate. Cannot update '||:new.);
WHEN nforeign_key
THEN raise_application_error(-20101, v_error_relay||' '||' YOUR MESSAGE HERE '||:new.);
END;

Answer 1

Mark:
Ordinarily, I not really a critical guy, but that thing is such a mess that I have to comment. I won't mention the complete lack of bind variables (which leads to the shared pool and hard parsing concerns), but as posted it won't even compile. I had some time to kill, so.
For starters, the big query in your function gets:
ORA-01467: sort key too long
on my 9.2.0.6 instance with 16K blocksize, and on my 9.2.0.1 instance with an 8K blocksize. Interestingly, it does work on my 8.1.7.4 instance with 8K blocks. So, I had to limit it to 15 columns.
You give no function name at all. Based on the trigger code, I assume the function should be documents_cons_dml. I also added a paramter to pass the table name since one could conceivably have more than one table in an application.
I also took the liberty of fixing your extend problem. In your code, you extend the array by one in the first iteration through the loop, by two in the second and so on. Which is why you need the delete loop at the end.
There is no definition for the DbCons_documents_Array that the function returns, so I assumed something like:
SQL> CREATE TYPE dbconstraint_documents_rec AS OBJECT (
  2     constraint_name   VARCHAR2(30),
  3     table_name        VARCHAR2(30),
  4     constraint_column VARCHAR2(30),
  5     constraint_where  VARCHAR2(4000),
  6     column_position   VARCHAR2(1) );
  7  /
Type created.
SQL> CREATE TYPE DbCons_documents_Array AS
  2     VARRAY(50) OF dbconstraint_documents_rec;
  3  /
Type created.I used the names that you used in the trigger, although the names don't seem to match with the column contents, must be code re-use.
So, now the function looks like:
SQL> CREATE FUNCTION documents_cons_dml (p_table_name IN VARCHAR2)
  2    RETURN DbCons_documents_Array AS
  3
  4     dbdata DbCons_documents_Array := DbCons_documents_Array();
  5     i NUMBER := 1;
  6  BEGIN
  7     FOR cns_rec IN(SELECT child.child_cons_name clchild_cons_name,
  8                           child.parent_cons_name clparent_cons_name,
  9                           child.child_columns clchild_columns,
10                           parent.parent_cons_name pparent_cons_name,
11                           parent.parent_tname pparent_tname,
12                           child.child_tname clchild_tname,
13                           CONCAT(CONCAT('"',REPLACE(REPLACE(parent.parent_columns,'"',''),'''','')),'"') pparent_columns,
14                           child.parent_cons_type pparent_cons_type
15                    FROM (SELECT a.table_name child_tname,
16                                 a.constraint_name child_cons_name,
17                                 NVL(b.r_constraint_name,a.constraint_name) parent_cons_name,
18                                 b.constraint_type parent_cons_type,
19                                 MAX(DECODE(position, 1, '"'||column_name||'"',NULL)) ||
20                                 MAX(DECODE(position, 2,', "'||column_name||'"',NULL)) ||
21                                 MAX(DECODE(position, 3,', "'||column_name||'"',NULL)) ||
22                                 MAX(DECODE(position, 4,', "'||column_name||'"',NULL)) ||
23                                 MAX(DECODE(position, 5,', "'||column_name||'"',NULL)) ||
24                                 MAX(DECODE(position, 6,', "'||column_name||'"',NULL)) ||
25                                 MAX(DECODE(position, 7,', "'||column_name||'"',NULL)) ||
26                                 MAX(DECODE(position, 8,', "'||column_name||'"',NULL)) ||
27                                 MAX(DECODE(position, 9,', "'||column_name||'"',NULL)) ||
28                                 MAX(DECODE(position,10,', "'||column_name||'"',NULL)) ||
29                                 MAX(DECODE(position,11,', "'||column_name||'"',NULL)) ||
30                                 MAX(DECODE(position,12,', "'||column_name||'"',NULL)) ||
31                                 MAX(DECODE(position,13,', "'||column_name||'"',NULL)) ||
32                                 MAX(DECODE(position,14,', "'||column_name||'"',NULL)) ||
33                                 MAX(DECODE(position,15,', "'||column_name||'"',NULL)) child_columns
34                          FROM user_cons_columns a, user_constraints b
35                          WHERE a.constraint_name = b.constraint_name and
36                                b.constraint_type IN ( 'U', 'R' )
37                          GROUP BY a.table_name, a.constraint_name,
38                                   b.r_constraint_name,b.constraint_type ) child,
39                         (SELECT a.constraint_name parent_cons_name,
40                                 a.table_name parent_tname,
41                                 MAX(DECODE(position, 1, '"'||column_name||'"',NULL)) ||
42                                 MAX(DECODE(position, 2,', "'||column_name||'"',NULL)) ||
43                                 MAX(DECODE(position, 3,', "'||column_name||'"',NULL)) ||
44                                 MAX(DECODE(position, 4,', "'||column_name||'"',NULL)) ||
45                                 MAX(DECODE(position, 5,', "'||column_name||'"',NULL)) ||
46                                 MAX(DECODE(position, 6,', "'||column_name||'"',NULL)) ||
47                                 MAX(DECODE(position, 7,', "'||column_name||'"',NULL)) ||
48                                 MAX(DECODE(position, 8,', "'||column_name||'"',NULL)) ||
49                                 MAX(DECODE(position, 9,', "'||column_name||'"',NULL)) ||
50                                 MAX(DECODE(position,10,', "'||column_name||'"',NULL)) ||
51                                 MAX(DECODE(position,11,', "'||column_name||'"',NULL)) ||
52                                 MAX(DECODE(position,12,', "'||column_name||'"',NULL)) ||
53                                 MAX(DECODE(position,13,', "'||column_name||'"',NULL)) ||
54                                 MAX(DECODE(position,14,', "'||column_name||'"',NULL)) ||
55                                 MAX(DECODE(position,15,', "'||column_name||'"',NULL)) parent_columns
56                          FROM user_cons_columns a, user_constraints b
57                          WHERE a.constraint_name = b.constraint_name and
58                                b.constraint_type IN ( 'P', 'U', 'R' )
59                          GROUP BY a.table_name, a.constraint_name ) parent
60                    WHERE child.parent_cons_name = parent.parent_cons_name and
61                          child.child_tname = upper(p_table_name)) LOOP
62        dbdata.extend;
63        dbdata(i) := dbconstraint_documents_rec(cns_rec.pparent_cons_name,
64                                                cns_rec.clchild_tname,
65                                                cns_rec.pparent_tname,
66                                                cns_rec.pparent_columns,
67                                                cns_rec.pparent_cons_type);
68        i := i+1;
69     END LOOP;
70     RETURN dbdata;
71  END;
72  /
Function created.
SQL> CREATE TABLE t (ID NUMBER PRIMARY KEY, descr VARCHAR2(10));
Table created.
SQL> CREATE TABLE t1 (idt1 NUMBER PRIMARY KEY, descr VARCHAR2(10));
Table created.
SQL> ALTER TABLE t ADD CONSTRAINT t_fk
  2  FOREIGN KEY (id) REFERENCES t1 (idt1);
Table altered.Now for the trigger. Once I got rid of the schema owner cdrl5 in the dbconstraint_documents_rec call it actually compiled first time. So, my trigger looks like:
SQL> CREATE OR REPLACE TRIGGER t_bi
  2  BEFORE INSERT ON t
  3  FOR EACH ROW
  4  DECLARE
  5     v_sql VARCHAR2(32000);
  6     v_literal_value VARCHAR2(100);
  7     v_error_relay VARCHAR2(4000);
  8     v_db_values NUMBER := 1;
  9     v_dup_count NUMBER;
10     nforeign_key EXCEPTION;
11
12     TYPE DupRecordType IS REF CURSOR;
13     dup_rec_cv DupRecordType;
14
15     dbdata DbCons_Documents_Array := DbCons_Documents_Array(dbconstraint_documents_rec(null,null,null,null,null));
16
17     TYPE tokenTableType IS TABLE OF VARCHAR2(4000) INDEX BY BINARY_INTEGER;
18     tokenChar VARCHAR2(4000) := '," ';
19     tokens tokenTableType;
20     vCnt INTEGER := 1;
21     myLine VARCHAR2(4000) := NULL;
22     Line VARCHAR2(4000) := NULL;
23     vPos INTEGER := 1;
24
25     TYPE form_rec IS RECORD (
26        table_name VARCHAR2(100),
27        db_column VARCHAR2(100),
28        db_col_value VARCHAR2(1000));
29
30     TYPE form_type IS TABLE OF form_rec INDEX BY BINARY_INTEGER;
31     web_form_array form_type;
32
33  BEGIN
34     dbdata.DELETE;
35  -- NOTE: Load the below table(with values specified) for each table constraint
36
37     web_form_array(v_db_values).table_name := 'T';
38     web_form_array(v_db_values).db_column := 'ID';
39     web_form_array(v_db_values).db_col_value := :new.ID;
40     v_db_values := v_db_values +1;
41
42     FOR cns_rec IN(SELECT *
43                    FROM TABLE ( CAST(documents_cons_dml('T') AS DbCons_documents_Array ))) LOOP
44        line := cns_rec.constraint_where;
45        v_sql := 'SELECT count(*) FROM '||cns_rec.constraint_column;
46        IF INSTR(line,',',1,1) <= 0 THEN
47           FOR find_web_frm_val IN 1 .. web_form_array.COUNT LOOP
48              IF cns_rec.table_name = web_form_array(find_web_frm_val).table_name AND
49                 REPLACE(line,'"','') = web_form_array(find_web_frm_val).db_column THEN
50
51                 v_literal_value :=CONCAT(CONCAT('''',web_form_array(find_web_frm_val).db_col_value),'''');
52                 v_sql := v_sql||' WHERE '||' '||web_form_array(find_web_frm_val).db_column||' = '||v_literal_value;
53              END IF;
54           END LOOP;
55        ELSE
56           WHILE (vPos <= LENGTH(line)) LOOP
57              IF (LENGTH(REPLACE(tokenChar,substr(line, vPos, 1), '')) = LENGTH(tokenChar)) THEN
58                 myLine := myLine || substr(line, vPos, 1);
59              ELSIF (myLine IS NOT NULL) THEN
60                 tokens(vCnt) := myLine;
61                 FOR find_web_frm_val IN 1 .. v_db_values LOOP
62                    IF cns_rec.table_name = web_form_array(find_web_frm_val).table_name AND
63                          MYLine = web_form_array(find_web_frm_val).db_column THEN
64                       v_literal_value := CONCAT(CONCAT('''',web_form_array(find_web_frm_val).db_col_value),'''');
65                    END IF;
66                 END LOOP;
67                 IF vCnt = 1 THEN
68                    v_sql := v_sql||' WHERE '||' '||myLine||' = '||v_literal_value;
69                 ELSE
70                    v_sql := v_sql||' AND '||' '||myLine||' = '||v_literal_value;
71                 END IF;
72                 myLine := null;
73                 vCnt := vCnt + 1;
74              END IF;
75              vPos := vPos + 1;
76           END LOOP;
77
78           IF (myLine IS NOT NULL) THEN
79              tokens(vCnt) := myLine;
80           END IF;
81           vCnt := 1;
82           vPos := 1;
83        END IF;
84
85        OPEN dup_rec_cv FOR v_sql;
86        FETCH dup_rec_cv INTO v_dup_count;
87        CLOSE dup_rec_cv;
88        IF cns_rec.column_position = 'R' THEN
89           IF v_dup_count <= 0 THEN
90              v_error_relay := 'The form field value for Database Column '||' '||line||' '||' that was entered does not exist';
91              RAISE nforeign_key;
92           END IF;
93        ELSIF cns_rec.column_position = 'U' THEN
94           IF v_dup_count > 0 THEN
95              RAISE DUP_VAL_ON_INDEX;
96           END IF;
97        END IF;
98     END LOOP;
99  EXCEPTION
100     WHEN DUP_VAL_ON_INDEX THEN
101        raise_application_error(-20101, 'Attempted to update duplicate. Cannot update '||:new.ID);
102     WHEN nforeign_key THEN
103        raise_application_error(-20101, v_error_relay||' '||' YOUR MESSAGE HERE '||:new.ID);
104  END;
105  /
Trigger created.So, lets try this puppy out.
SQL> INSERT INTO t1 VALUES (1, 'T1 ONE');
1 row created.
SQL> COMMIT;
Commit complete.I want at least one valid value to make sure I can actually insert something without dying on the trigger.
SQL> INSERT INTO t VALUES (1, 'T One');
1 row created.
SQL> COMMIT;
Commit complete.Which we can. Now lets test the Primary Key.
SQL> INSERT INTO t VALUES (1, 'T One');
INSERT INTO t VALUES (1, 'T One')
ERROR at line 1:
ORA-00001: unique constraint (OPS$ORACLE.SYS_C0027113) violatedOOPS, that's Oracle's message. Well, maybe it's because you are only checking cns_rec.column_position for R or U and my constraint is a P, and by the way, your function does not return the Primary Key for the table passed at all.
So, lets try the foreign key:
SQL> INSERT INTO t VALUES (2, 'T Two');
INSERT INTO t VALUES (2, 'T Two')
ERROR at line 1:
ORA-02291: integrity constraint (OPS$ORACLE.T_FK) violated - parent key not foundOOPS. So, for every valid insert I am doing a huge amount of extra work, and I still get Oracle's errors when it's wrong. If I have screwed something up in the set-up, please feel free to post a working example exactly as I did here.
John