I'm using Firebird 2.5.0. I know a value and need to find all tables, columns in which it occurs.
I created procedure:
CREATE OR ALTER PROCEDURE NEW_PROCEDURE (
searching_value varchar(30))
returns (
table_with_value varchar(100),
column_with_value varchar(100))
as
declare variable all_tables varchar(50);
declare variable all_columns varchar(50);
declare variable all_values varchar(50);
begin
FOR SELECT
r.rdb$relation_name, f.rdb$field_name
from rdb$relation_fields f
join rdb$relations r on f.rdb$relation_name = r.rdb$relation_name
and r.rdb$view_blr is null
and (r.rdb$system_flag is null or r.rdb$system_flag = 0)
order by 1, f.rdb$field_position INTO :all_tables, :all_columns
DO
BEGIN
FOR SELECT all_columns FROM all_tables
INTO :all_Values
DO
BEGIN
IF (SEARCHING_VALUE = all_Values) THEN
BEGIN
table_With_Value = all_Tables;
column_With_Value = all_Columns;
SUSPEND;
END
END
END
END^
When I run it I get error message:
Undefined name.
Dynamic SQL Error.
SQL error code = -204.
Table unknown.
ALL_TABLES.
At line 21, column 13.
So in this select statement "SELECT all_columns FROM all_tables" it is not taking values from previous for select statement but just trying to find table all_tables. How to fix it?
The problem is that all_columns is considered to be a colum name and all_tables a table name and not your variables in:
SELECT all_columns FROM all_tables
You can't parametrize objectnames in a query like this. Also note that if it had been possible to parametrize object names, you would have had to use :all_columns and :all_tables for disambiguation.
Instead you will need to create a dynamic SQL statement and execute that with EXECUTE STATEMENT (or more specifically: FOR EXECUTE STATEMENT).
In this case:
FOR EXECUTE STATEMENT 'SELECT "' || all_columns || '" FROM "' || all_tables || '"'
INTO :all_values
DO
BEGIN
/* .... */
END
I have quoted the object names to account for case sensitive column and table names (or identifiers that are invalid unquoted). Constructing a query like this might leave you open to SQL injection if the values are obtained from another source than the Firebird metadata tables.
Related
I need to get an id from a table, whose table name is defined by running another query.
I tried to implement it by defining a variable that saves the results from the first query. Then I created a second query that consumes the table name from the first one.
define tablename = (SELECT table_name FROM tables_names WHERE row_id = 147);
define rowid = SELECT row_id FROM &tablename WHERE title is NULL;
select * from &rowid;
However it doesn't work. I also tried to create a stored procedure, but I don't understand how it should work either:
DECLARE
tablename varchar(128);
rowid int;
BEGIN
SELECT table_name INTO tablename FROM tables_names WHERE row_id = 147);
SELECT row_id INTO rowid FROM &tablename WHERE title is NULL;
END;
The output should give me the expected rowid. I'm not an Oracle expert and this seems like a simple thing, but I don't know how to achieve it.
Use execute immediate as following:
DECLARE
rowid_ int; -- dont use oracle reserved words as variable name.
-- added _ after rowid
BEGIN
EXECUTE IMMEDIATE 'SELECT row_id FROM '
|| (SELECT table_name FROM tables_names WHERE row_id = 147)
|| ' WHERE title is NULL' INTO ROWID_;
-- do something with rowid_ or other logic
END;
/
Cheers!!
This is called dynamic sql.
Edit the procedure and have it do
EXECUTE IMMEDIATE
"SELECT row_id INTO :x FROM " || tablename || " WHERE title IS NULL"
USING rowid;
This is from memory so it might not work, but should give you a good start on how to do it
I try use variable inside "from" SELECT COUNT(*) FROM :T_NAME, but is not work. How can i fix this? This my code:
SET TERM ^ ;
CREATE OR ALTER PROCEDURE Myfunction
RETURNS(
T_NAME varchar(100),
NUM_RECORDS integer
)
AS
BEGIN
FOR SELECT RDB$RELATION_NAME FROM RDB$RELATIONS
WHERE (RDB$SYSTEM_FLAG <> 1 OR RDB$SYSTEM_FLAG IS NULL) AND RDB$VIEW_BLR IS NULL
ORDER BY RDB$RELATION_NAME
INTO :T_NAME
DO
BEGIN
SELECT COUNT(*) FROM :T_NAME
INTO :NUM_RECORDS;
SUSPEND;
END
END^
SET TERM ; ^
You can't parametrize object names. You will need to dynamically build the query (which if you aren't careful may leave you open to SQL injection).
Specifically you need to use:
...
BEGIN
EXECUTE STATEMENT 'select count(*) from "' || T_NAME || '"'
INTO :NUM_RECORDS;
SUSPEND;
END
This should be safe except for table names that contain double quotes. I haven't explicitly checked the behavior with single quotes in an object name, which technically is possible. You may need to take extra steps to protect against these forms of SQL injection if you use this in real production code.
Goal: Use a given subquery's results (a single column with many rows of names) to act as the outer select's selection field.
Currently, my subquery is the following:
SELECT column_name
FROM information_schema.columns
WHERE table_name = 'test_table' AND column_name not in ('colRemove');
What I am doing in this subquery is grabbing all the column names from a table (i.e. test_table) and outputting all except for the column name specified (i.e. colRemove). As stated in the "goal", I want to use this subquery as such:
SELECT (*enter subquery from above here*)
FROM actual_table
WHERE (*enter specific conditions*)
I am working on a Netezza SQL server that is version 7.0.4.4. Ideally, I would like to make the entire query executable in one line, but for now, a working solution would be much appreciated. Thanks!
Note: I do not believe that the SQL extensions has been installed (i.e. arrays), but I will need to double check this.
A year too late, here's the best I can come up with but, as you already noticed, it requires a stored procedure to do the dynamic SQL. The stored proc creates a view with the all the columns from the source table minus the one you want to exclude.
-- Create test data.
CREATE TABLE test (firstcol INTEGER, secondcol INTEGER, thirdcol INTEGER);
INSERT INTO test (firstcol, secondcol, thirdcol) VALUES (1, 2, 3);
INSERT INTO test (firstcol, secondcol, thirdcol) VALUES (4, 5, 6);
-- Install stored procedure.
CREATE OR REPLACE PROCEDURE CreateLimitedView (varchar(ANY), varchar(ANY)) RETURNS BOOLEAN
LANGUAGE NZPLSQL AS
BEGIN_PROC
DECLARE
tableName ALIAS FOR $1;
columnToExclude ALIAS FOR $2;
colRec RECORD;
cols VARCHAR(2000); -- Adjust as needed.
isfirstcol BOOLEAN;
BEGIN
isfirstcol := true;
FOR colRec IN EXECUTE
'SELECT ATTNAME AS NAME FROM _V_RELATION_COLUMN
WHERE
NAME=UPPER('||quote_literal(tableName)||')
AND ATTNAME <> UPPER('||quote_literal(columnToExclude)||')
ORDER BY ATTNUM'
LOOP
IF isfirstcol THEN
cols := colRec.NAME;
ELSE
cols := cols || ', ' || colRec.NAME;
END IF;
isfirstcol := false;
END LOOP;
-- Should really check if 'LimitedView' already exists as a view, table or synonym.
EXECUTE IMMEDIATE 'CREATE OR REPLACE VIEW LimitedView AS SELECT ' || cols || ' FROM ' || quote_ident(tableName);
RETURN true;
END;
END_PROC
;
-- Run the stored proc to create the view.
CALL CreateLimitedView('test', 'secondcol');
-- Select results from the view.
SELECT * FROM limitedView WHERE firstcol = 4;
FIRSTCOL | THIRDCOL
----------+----------
4 | 6
You could have the stored proc return a resultset directly but then you wouldn't be able to filter results with a WHERE clause.
I have the following table name template, there are a couple with the same name and a number at the end: fmj.backup_semaforo_geo_THENUMBER, for example:
select * from fmj.backup_semaforo_geo_06391442
select * from fmj.backup_semaforo_geo_06398164
...
Lets say I need to select a column from every table which succeeds with the 'fmj.backup_semaforo_geo_%' filter, I tried this:
SELECT calle --This column is from the backup_semaforo_geo_# tables
FROM (SELECT table_name
FROM all_tables
WHERE owner = 'FMJ' AND table_name LIKE 'BACKUP_SEMAFORO_GEO_%');
But I'm getting the all_tables tables name data:
TABLE_NAME
----------
BACKUP_SEMAFORO_GEO_06391442
BACKUP_SEMAFORO_GEO_06398164
...
How can I achieve that without getting the all_tables output?
Thanks.
Presumably your current query is getting ORA-00904: "CALLE": invalid identifier, because the subquery doesn't have a column called CALLE. You can't provide a table name to a query at runtime like that, unfortunately, and have to resort to dynamic SQL.
Something like this will loop through all the tables and for each one will get all the values of CALLE from each one, which you can then loop through. I've used DBMS_OUTPUT to display them, assuming you're doing this in SQL*Plus or something that can deal with that; but you may want to do something else with them.
set serveroutput on
declare
-- declare a local collection type we can use for bulk collect; use any table
-- that has the column, or if there isn't a stable one use the actual data
-- type, varchar2(30) or whatever is appropriate
type t_values is table of table.calle%type;
-- declare an instance of that type
l_values t_values;
-- declare a cursor to generate the dynamic SQL; where this is done is a
-- matter of taste (can use 'open x for select ...', then fetch, etc.)
-- If you run the query on its own you'll see the individual selects from
-- all the tables
cursor c1 is
select table_name,
'select calle from ' || owner ||'.'|| table_name as query
from all_tables
where owner = 'FMJ'
and table_name like 'BACKUP_SEMAFORO_GEO%'
order by table_name;
begin
-- loop around all the dynamic queries from the cursor
for r1 in c1 loop
-- for each one, execute it as dynamic SQL, with a bulk collect into
-- the collection type created above
execute immediate r1.query bulk collect into l_values;
-- loop around all the elements in the collection, and print each one
for i in 1..l_values.count loop
dbms_output.put_line(r1.table_name ||': ' || l_values(i));
end loop;
end loop;
end;
/
May be a dynamic SQL in a PLSQL program;
for a in (SELECT table_name
FROM all_tables
WHERE owner = 'FMJ' AND table_name LIKE 'BACKUP_SEMAFORO_GEO_%')
LOOP
sql_stmt := ' SELECT calle FROM' || a.table_name;
EXECUTE IMMEDIATE sql_stmt;
...
...
END LOOP;
Im using a DB2 Database. What would be a suitable SQL query to find out if a column is exists in a table or list of tables?
e.g
if "column_name" is found in "table name" or [list of table names]
return true or the name of tables that have that column.
Many thanks.
Tested on DB2 z/OS 9.1 and LUW 9.7:
SELECT STRIP(TBCREATOR) || '.' || STRIP(TBNAME)
FROM SYSIBM.SYSCOLUMNS
WHERE NAME = 'your_col'
AND TBNAME IN ('list', 'of', 'tables')
If you only want results from a specific schema you might add AND TBCREATOR = 'your_schema' to the end of the query.
Use SYSCAT.COLUMNS catalog view:
SELECT TABNAME
FROM SYSCAT.COLUMNS
WHERE
TABNAME IN ('table name 1', 'table name 2') AND
COLNAME = 'column_name';
Another way to do this is with error handling:
declare v_sql varchar(1000);
declare col_missing integer default 0;
declare col_does_not_exist condition for sqlstate '42703';
declare continue handler for col_does_not_exist set col_missing = 1;
set v_sql = 'select table.foo from table';
execute immediate v_sql;
if col_missing = 1 then
--Do something if column foo doesn't exist.
end if;
This method will work on session tables, and you can also use it on an object even if you don't know whether it is a table, view, alias, etc.
It is important to specify table.foo rather than just the column name, as otherwise the existence of another object (such as a variable) called foo would break the test.
This continue handler will mask any other errors for columns missing within the scope, so it is best to limit the scope to just the test you want to do.