ORA-01489: result of string concatenation is too long
The sql query below is meant to extract data from the database as pipe delimited and spools it to a text file on unix
select a||'|'||b||'|'||c||'|'||d from table
union
select a||'|'||b||'|'||c||'|'||d from table
It some times gives the ORA error ORA-01489: result of string concatenation is too long
This looks like occuring if the select exceeds 4000 limit
I tried using to_clob but this works only with "union all"
Is there a way i can get around this problem
Do the union before the concatenation.
select to_clob(a) ||'|'|| to_clob(b) ||'|'|| to_clob(c) ||'|'|| to_clob(d) from
(
select a, b, c, d from table1
union
select a, b, c, d from table2
)
As you have found out, using to_clob has its limitations. And to be honest, I think you are using a fine tool (a RDBMS) as a blunt paleolithic weapon.
The easiest way to get around the problem is to do the concatenation in-situ, in your code, as opposed to doing it with SQL. There is a maximum length limit for concatenation operations in Oracle (4k length), and there is a limit on where you can use to_clob.
So if you have those two hard limits, the most sensible thing is to do what I suggested you (do the concatenation in code) instead of trying to subvert or find an almost-magical way to work around that.
select a, b, c, d from table A
union
select a, b, c, d from table B
Then take the resulting resultset (or whatever language-specific construct you use) and concatenate the fields in your application code.
This way I use to find procedure
select name, LISTAGG(text, ' ' ON OVERFLOW TRUNCATE) WITHIN GROUP (ORDER BY name) from all_source where name in
(select distinct name from all_source where type = 'PROCEDURE' and text like '%P_%') and text like '% OUT %' group by name;
The interesting point is that the table all_source have the information of every procedure in divided by rows, which do processing tricky. For that reason first, I concatenate the rows for every procedure, and second set the option ON OVERFLOW TRUNCATE for avoid the string overflow; of course it works for me because I only need the procedure declaration.
In this case I'm looking for procedures that contain in the name "P_" and have attributes of type OUT.
The same could be applied for search functions only changing type = 'PROCEDURE' by type = 'FUNCTION'
Hope this help.
Related
Let say I have tables A,B,C,......,Z and I want to count all the entries in the tables and combine the results like so:
SELECT 'A' AS A, count(*) from USER.A UNION
.
.
.
SELECT 'J' AS J, count(*) from USER.J UNION
.
.
SELECT 'Z' AS 'Z' COUNT(*) from USER.Z
I want to avoid all above hassle. How can I do this in a smart way?.
I tend to do this by writing a query using the user_tables Meta information View and first time selecting text that is actually an sql query:
SELECT 'select '''||TABLE_NAME||''', count(*) from '||TABLE_NAME||'union all' FROM USER_TABLES
Running that in your query tool will produce a grid of rows that are actually sql queries in their own right. Copying them out of the results grid, pasting them into the query window (remove the trailing UNION ALL) and running them again produces data for each table
select 'a', count(*) from a union all
select 'b', count(*) from b union all ....
To get more involved and include column names, there's a USER_TAB_COLUMNS view that cites info about columns (e.g. You could write a query that generates queries that search any varchar columns for a particular value)
If you get really involved it can be cleaner to use placeholders in the string and REPLACE them:
SELECT REPLACE(REPLACE(REPLACE(
'select ''{o}.{t}'' as tname, ''{c}'' as cname
from {o}.{t} where
{c} like ''hello%'' or
{c} like ''goodbye%'' union all'
--to add more placeholders copy paste these lines
--and ensure there is the same number of REPLACE
--as there are numbers of lines
, '{t}', TABLE_NAME)
, '{c}', COLUMN_NAME)
, '{o}', OWNER)
FROM ALL_TAB_COLUMNS
WHERE DATA_TYPE = 'VARCHAR'
This is massively cleaner than starting and stopping your string all the time with || concatenation. I've deliberately uppercase the outer query and lowercase the inner query so you can tell which part is which
To add more placeholders, put additional REPLACE( at the top and copy paste in place the lines underneath that begin with a comma. Example copy , '{t}', table_name) paste and change to , '{d}', data_type) add another REPLACE( at the top and now you have a {d} placeholder you can use anywhere in the first string (the sql query pattern) to signify the data type
Say I have a table with the following data:
You can see columns a, b, & c have a lot of redundancies. I would like those redundancies removed while preserving the site_id info. If I exclude the site_id column from the query, I can get part of the way there by doing SELECT DISTINCT a, b, c from my_table.
What would be ideal is a SQL query that could turn the site IDs relevant to a permutation of a/b/c into a delimited list, and output something like the following:
Is it possible to do that with a SQL query? Or will I have to export everything and use a different tool to remove the redundancies?
The data is in a SQL Server DB, though I'd also be curious how to do the same thing with postgres, if the process is different.
For SQL Server, you can use the FOR XML trick as found in the accepted answer in this post.
For your scenario it would look something like this:
SELECT a, b, c, SiteIds =
STUFF((SELECT ', ' + SiteId
FROM your_table t2
WHERE t2.a = t1.a AND t2.b = t1.b AND t2.c = t1.c
FOR XML PATH('')), 1, 2, '')
FROM your_table t1
GROUP BY a, b, c
For Postgres:
select a,b,c, string_agg(site_id::varchar, ',')
from my_table
group by a,b,b;
I assume site_id is a number, and as string_agg() only accepts character value, this needs to be casted to a character string for the aggregation. This is what site_id::text does. Alternatively you can use the cast() operator: string_agg(cast(site_id as varchar), ',')
This is generally known as String Aggregation. Many RDBMS's have the ability baked in, and many others don't.
In Postgres you just use the STRING_AGG(<field>, <delimiter>) function, and make sure to add a GROUP BY for your non-aggregated fields. Simple stuff.
In SQL Server.. not so pretty, but folks have functions and whatnot that will allow you to do this (like in this Q/A)
I have a SQL table as shown below. I want to generate strings using the 2 fields in my table.
A B
M1 tiger
M1 cat
M1 dog
M3 lion
I want to read in this table, count the number of rows, and store it in string variables like String1 = M1_tiger, String2 = M1_cat, etc. What's the best way to do this?
You could do a concat type query.
SELECT (Table.A + '_' + Table.B) AS A_B, COUNT(*) AS RowsCount FROM Table
I'm asuming the your table name is "Table", the result where you will find the strings you want would be the column named A_B, each record will have two things in each record, one would be the string you asked for, the other column would always be the same thing, the total number of records on you table.
The count part is kinda easy but check this link so you can use the specific count you need: http://www.w3schools.com/sql/sql_func_count.asp
You can try this:
SELECT CONCAT(A, '_', B) FROM yourtable
When you say "read in this table", do you mean read it into a programming language like C#? Or do you want to dynamically create sql variables?
You may want to use a table variable to store your strings rather than individual variables. Regarding getting the row number, you could use something like:
WITH CTE AS
(
SELECT A, B,
ROW_NUMBER() OVER (order by OrderDate) AS 'RowNumber'
FROM MyTable
)
SELECT A,B,RowNumber FROM CTE
See this answer for more on how you may choose to use the table variable.
SQL: Dynamic Variable Names
If your are using Oracle, you can also do it like:
select A ||'_'||B
from yourTable
Solution for PostgreSQL
CREATE SEQUENCE one;
SELECT array_to_string(array_agg(concat('String',nextval('one'),' = ',A,'_',B)), ', ')
AS result
FROM test_table;
DROP SEQUENCE one;
Explanation:
Create a temporary sequence 'one' in order to use nextval function.
nextval('sequence') - advance sequence and return new value.
concat('input1', ...) - concatenate all arguments.
array_agg('input1', ...); - input values, including nulls,
concatenated into an array.
array_to_string('array', 'delimiter') - concatenates array elements
using supplied delimiter and optional null string.
Drop the sequence 'one'.
The output of the query (for two test rows in test_table):
result
-------------------------------------------
String1 = M1_tiger, String2 = M1_cat
(1 row)
If I select a column in a table, say 10 rows, can I use SQL to insert a 'please select' row into the first position using SQL only? I want to insert it in the result set only - not the database.
First you should know this is a bad idea.
You are confusing your presentation layer and your database layer. Forcing SQL to do things like output status messages or feedback to users is an antipattern to be avoided.
That being said, if the column is of a string type (char, varchar, etc), you can do something like:
SELECT 'Please Select'
UNION ALL
SELECT TOP 10 Varcharfield
FROM Mytable
If it's numeric then no unless you cast it to a string type.
Here's something you can try:
SELECT u.YourVarcharColumnName
FROM (
SELECT 1 AS rID, 'Please select' AS YourVarcharColumnName
UNION
SELECT 2 AS rID, YourVarcharColumnName
FROM YourTableName
) u
ORDER BY u.rID;
I placed rID in place and sorted by it as an extreme-case-measure when your intended first rowset does not come out on top...
However, you should keep in mind that YourVarcharColumnName should be (as it says) a string. You'll have to convert it to a string if it's a non-string column.
As #JNK mentioned it.. I thought I should edit my post as well:
Please first try:
SELECT 'Please select' AS YourVarcharColumnName
UNION
SELECT YourVarcharColumnName
FROM YourTableName
Which is similar to what the others have posted. If you ever experience what I've been unfortunate to encounter and 'Please select' doesn't come out on top, please refer to the query I posted at the top.. Thanks!
SELECT '(Please select)'
UNION
SELECT ColumnName FROM TableName
The decode works like this:
SELECT DECODE('col1', 'x', 'result1','y','result2') resultFinal
FROM table1;
It possible to accomplish this in sql:
SELECT *
FROM (SELECT DECODE('col1', 'x' (someSql),'y',(someOthersql)) result
FROM table1)
So instead of result1 and result2 being fixed values, they would be sql statements. If not possible, how can I achieve the same result without a stored proc.
EDIT: someSql and someOthersql are both complex queries with many joins returining many but same number of cols with same col names.
If someSql and someOthersql return exactly one row with one column, then this should work.
The following works for me:
select decode(col, (select 'foo' from dual), (select 'bar' from dual))
from some table
I think you may need to create a PL/SQL procedure to handle the complex logic.