Query:
CREATE TABLE SRC(SRC_STRING VARCHAR(20))
CREATE OR REPLACE TABLE TGT(tgt_STRING VARCHAR(10))
INSERT INTO SRC VALUES('JKNHJYGHTFGRTYGHJ')
INSERT INTO TGT(TGT_STRING) SELECT SRC_STRING::VARCHAR(10) FROM SRC
Error: String 'JKNHJYGHTFGRTYGHJ' is too long and would be truncated
Is there any way we can enable enforce length(not for COPY command) while inserting data from high precision to low precision column?
I'd recommend using the SUBSTR( ) function, to pick the piece of data you want, example as follows where I take the first 10 characters (if available, if there were only 5 it'd use those 5 characters).
CREATE OR REPLACE TEMPORARY TABLE SRC(
src_string VARCHAR(20));
CREATE OR REPLACE TEMPORARY TABLE TGT(
tgt_STRING VARCHAR(10));
INSERT INTO src
VALUES('JKNHJYGHTFGRTYGHJ');
INSERT INTO tgt(tgt_string)
SELECT SUBSTR(src_string, 1, 10)
FROM SRC;
SELECT * FROM tgt; --JKNHJYGHTF
Here's the documentation on the function:
https://docs.snowflake.com/en/sql-reference/functions/substr.html
Related
Can I do something like this, column is of type nchar(8), but the string I wanted to store in the table is longer than that.
The reason I am doing this is because I want to convert from one table to another table. Table A is nchar(8) and Table B is nvarchar(100). I want all characters in Table B transfer to Table A without missing any single character.
If the nvarchar(100) contains only latin characters with a length up to 16 chars, then you can squeeze the nvarchar(100) into the nchar(8):
declare #t table
(
col100 nvarchar(100),
col8 nchar(8)
);
insert into #t(col100) values('1234567890123456');
update #t
set col8 = cast(cast(col100 as varchar(100)) as varbinary(100))
select *, cast(cast(cast(col8 as varbinary(100)) as varchar(100)) as nvarchar(100)) as from8to100_16charsmax
from #t;
If you cannot modify A, then you cannot use it to store the data. Create another table for the overflow . . . something like:
create table a_overflow (
a_pk int primary key references a(pk),
column nvarchar(max) -- why stop at 100?
);
Then, you can construct a view to bring in the data from this table when viewing a:
create view vw_a as
select . . . , -- all the other columns
coalesce(ao.column, a.column) as column
from a left join
a_overflow ao
on ao.a_pk = a.pk;
And, if you really want to "hide" the view, you can create an insert trigger on vw_a, which inserts the appropriate values into the two tables.
This is a lot of work. Simply modifying the table is much simpler. That said, this approach is sometimes needed when you need to modify a large table and altering a column would incur too much locking overhead.
In a SQL Server database, one can use table variables like this:
declare #table as table (a int)
In an Azure Data Warehouse, that throws an error.
Parse error at line: 1, column: 19: Incorrect syntax near 'table'
In an Azure Data Warehouse, you can use temporary tables:
create table #table (a int)
but not inside functions.
Msg 2772, Level 16, State 1, Line 6 Cannot access temporary tables
from within a function.
This document from Microsoft says,
◦Must be declared in two steps (rather than inline): ◾CREATE TYPE
my_type AS TABLE ...; , then ◾DECLARE #mytablevariable my_type;.
But when I try this:
create type t as table (a int);
drop type t;
I get this :
Msg 103010, Level 16, State 1, Line 1 Parse error at line: 1, column:
8: Incorrect syntax near 'type'.
My objective is to have a function in an Azure Data Warehouse which uses a temporary table. Is it achievable?
Edit Start Here
Note that I am not looking for other ways to create one specific function. I have actually done that and moved on. I'm a veteran programmer but an Azure Data Warehouse rookie. I want to know if it's possible to incorporate some concept of temporary tables in an Azure Data Warehouse function.
Ok, I believe this is what you are after.
Firstly, this uses a Table Value Function, which are significantly faster than Scalar or Multi-statement Table value Functions.
Secondly, there was no use for a Table Variable, or Temporary Table, just some good odd string manipulation, a bit of maths, and a CTE. Definitely no expensive WHILE loop.
I've tested this against the examples in the link, and they all return the expected values.
USE Sandbox;
GO
CREATE FUNCTION ValidateHealthNumber (#HealthNumber varchar(10))
RETURNS TABLE
AS
RETURN
WITH Doubles AS(
SELECT CONVERT(tinyint,SUBSTRING(V.HN,O.P,1)) AS HNDigit,
CONVERT(tinyint,SUBSTRING(V.HN,O.P,1)) * CASE WHEN O.P % 2 = 0 THEN 1 ELSE 2 END ToAdd
FROM (VALUES(#HealthNumber)) V(HN)
CROSS APPLY (VALUES (1),(2),(3),(4),(5),(6),(7),(8),(9)) O(P)),
Parts AS (
SELECT CONVERT(tinyint,SUBSTRING(CONVERT(varchar(2),ToAdd),1,1)) AS FirstDigit, --We know that the highest value can be 18 (2*9)
CONVERT(tinyint,SUBSTRING(CONVERT(varchar(2),ToAdd),2,1)) AS SecondDigit --so no need for more than 2 digits.
FROM Doubles)
SELECT CASE RIGHT(#HealthNumber, 1) WHEN 10 - RIGHT(SUM(FirstDigit + SecondDigit),1) THEN 1 ELSE 0 END AS IsValid
FROM Parts;
GO
CREATE TABLE #Sample(HealthNumber varchar(10));
INSERT INTO #Sample
VALUES ('9876543217'), --Sample
('5322369835'), --Valid
('7089771195'), --Valid
('8108876957'), --Valid
('4395667779'), --Valid
('6983806917'), --Valid
('2790412845'), --not Valid
('5762696912'); --not Valid
SELECT *
FROM #Sample S
CROSS APPLY ValidateHealthNumber(HealthNumber) VHN;
GO
DROP TABLE #Sample
DROP FUNCTION ValidateHealthNumber;
If you don't understand any of this, please do ask.
No you can't. Object can't be created inside User Defined Functions (UDF). Use table variables instead.
If you want yo use user defined type, first create it outside the UDF and use it as a variable type within the UDF.
-- Create the data type
CREATE TYPE TestType AS TABLE
(
Id INT NOT NULL,
Col1 VARCHAR(20) NOT NULL)
GO
-- Create the tabled valued function
CREATE FUNCTION TestFunction
()
RETURNS
#Results TABLE
(Result1 INT, Result2 INT)
AS
BEGIN
-- Fill the table variable with the rows for your result set
DECLARE #Var1 TestType;
RETURN
END
GO
Hi everyone thanks so much for taking the time to read this.
I'd like to create a macro in Teradata that will create a table from another table based on specific parameters.
My original table consists of three columns patient_id, diagnosis_code and Date_of_birth
......
I'd like to build a macro that would allow me to specify a diagnosis code and it would then build the table consisting of data of all patients with that diagnosis code.
My current code looks like this
Create Macro All_pats (diag char) as (
create table pats as(
select *
from original_table
where diag = :diagnosis_code;)
with data primary index (patid);
I cant seem to get this to work - any tips?
Thanks once again
Your code has a semicolon in a wrong place and a missing closing bracket:
Create Macro All_pats (diag char) as (
create table pats as
(
select *
from original_table
where diag = :diagnosis_code
) with data primary index (patid);
);
Edit:
Passing multiple values as a delimited list is more complicated (unless you use Dynamic SQL in a Stored Procedure):
REPLACE MACRO All_lpats (diagnosis_codes VARCHAR( 1000)) AS
(
CREATE TABLE pats AS
(
SELECT *
FROM original_table AS t
JOIN TABLE (StrTok_Split_To_Table(1, :diagnosis_codes, ',')
RETURNS (outkey INTEGER,
tokennum INTEGER,
token VARCHAR(20) CHARACTER SET Unicode)
) AS dt
ON t.diag = dt.token
) WITH DATA PRIMARY INDEX (patid);
);
EXEC All_lpats('111,112,113');
As the name implies StrTok_Split_To_Table splits a delimited string into a table. You might need to adust the delimiter and the length of the resulting token.
Based on MSDN I see that numeric 10-19 using the same storage byte.
Is it mean that converting column from numeric (11,3) to numeric (18,3) will not use more storage space?
So, if it really like that, what are the risks? (Assuming that I need to do it for a 1 billion row table that may get numeric values that not fit 11,3).
It appears that SQL Server will use the lower storage option first (5 bytes), before reaching the max for that precision (9 bytes). But both (11,3) and (18,3) max out at 9 bytes. See script below.
As for your conversion of 1 billion rows, since it will be a widening conversion I don't think you will have any problems. You should test this with as close to to he full data set as possible. I'm not sure how long this alter would actually take.
USE tempdb
GO
CREATE TABLE MyTest (TestCol NUMERIC(11,3))
INSERT INTO dbo.MyTest ( TestCol ) VALUES( 99999999.999 )
INSERT INTO dbo.MyTest ( TestCol ) VALUES( 9.999 )
SELECT Testcol, DATALENGTH(Testcol) AS Size
FROM dbo.MyTest
CREATE TABLE MyTest2 (TestCol NUMERIC(18,3))
INSERT INTO dbo.MyTest2 ( TestCol ) VALUES( 999999999999999.999 )
INSERT INTO dbo.MyTest2 ( TestCol ) VALUES( 9.999 )
SELECT Testcol, DATALENGTH(Testcol) AS Size
FROM dbo.MyTest2
DROP TABLE dbo.MyTest
DROP TABLE dbo.MyTest2
I have a table designed like,
create table tbl (
id number(5),
data blob
);
Its found that the column data have
very small size data, which can be stored in raw(200):
so the new table would be,
create table tbl (
id number(5),
data raw(200)
);
How can I migrate this table to new design without loosing the data in it.
This is a bit lengthy method, but it works if you are sure that your data column values don't go beyond 200 in length.
Create a table to hold the contents of tbl temporarily
create table tbl_temp as select * from tbl;
Rem -- Ensure that tbl_temp contains all the contents
select * from tbl_temp;
Rem -- Double verify by subtracting the contents
select * from tbl minus select * from tbl_temp;
Delete the contents in tbl
delete from tbl;
commit;
Drop column data
alter table tbl drop column data;
Create a column data with raw(200) type
alter table tbl add data raw(200);
Select & insert from the temporary table created
insert into tbl select id, dbms_lob.substr(data,200,1) from tbl_temp;
commit;
We are using substr method of dbms_lob package which returns raw type data. So, the resulted value can be directly inserted.