I have more than 150 schemas in PostgreSQL, every time when I perform an action a new schema will be created with some random name with numbers. It is hard to find which is the new schema created.
I use \dn to list schemas in PostgreSQL, but it doesn't display schemas in created order. How do I list either recently created schema or schemas sorted by creation date?
Any schema has oid column - numeric unique identifier (that is increased only). So you can use ORDER BY oid DESC
SELECT * FROM pg_namespace ORDER BY oid DESC LIMIT 10;
Pavel's answer is good and may get you everything you need, but if you want more flexibility, I would recommend using event triggers:
CREATE TABLE schema_creation_history
(schema regnamespace primary key,
created timestamp with time zone not null default now()
);
CREATE FUNCTION log_schema_create() RETURNS event_trigger
LANGUAGE plpgsql AS
$$
BEGIN
INSERT INTO schema_creation_history (schema) SELECT objid::regnamespace FROM pg_event_trigger_ddl_commands();
END;
$$
;
CREATE EVENT TRIGGER schema_create_trigger
ON ddl_command_end
WHEN TAG IN ('CREATE SCHEMA')
EXECUTE FUNCTION log_schema_create();
# create schema test;
CREATE SCHEMA
# select * from schema_creation_history ;
schema | created
--------+------------------------------
test | 2019-09-11 12:32:21.16346+00
(1 row)
You could add another trigger for DROP SCHEMA to make sure the table is cleaned up.
Related
it it possible to write script in hana that crate temporary table that is based
on existing table (with no need to define columns and columns types hard coded ):
create local temporary table #mytemp (id integer, name varchar(20));
create temporary table with the same columns definitions and contain the
same data ? if so ..i ill be glad to get some examples
i am searching the internet for 2 days and i couldn't find anything useful
thanks
Creating local temporary tables based on dynamic structure definition is not supported in SQLScript.
The question would be: for what do you want to use it?
Instead of a local temp. table you can use a table variable in most cases.
By querying sys.table_columns view, you can get the list and properties of source table and build a dynamic CREATE script then Execute to create the table.
You can find SQL codes for a sample case at Create Table Dynamically on HANA Database
For table columns read
select * from sys.table_columns where table_name = 'TABLENAME';
Seems to work in the hana version I have. I'm not sure how to find out what the version.
PROCEDURE "xxx.yyy.zzz::MY_TEST"(
OUT "OUT_COL" NVARCHAR(200)
)
LANGUAGE SQLSCRIPT
SQL SECURITY INVOKER
AS
BEGIN
create LOCAL TEMPORARY TABLE #LOCALTEMPTABLE
as
(
SELECT distinct 'Cola' as out_col
FROM "SYNONYMS1"
);
select * from #LOCALTEMPTABLE ;
DROP TABLE #LOCALTEMPTABLE;
END
The newer HANA version (HANA 2 SPS 04 Patch 5 ( Build 4.4.17 )) supports your request:
create local temporary table #tempTableName' like "tableTypeName";
This should inherit the data types and all exact values from whatever query is in the parenthesis:
CREATE LOCAL COLUMN TEMPORARY TABLE #mytemp AS (
SELECT
"COLUMN1",
"COLUMN2",
"COLUMN3"
FROM MyTable
);
-- Now you can add the rest of your query here as such:
SELECT * FROM #mytemp
I suppose you can just write :
create column table #MyTempTable as ( select * from MySourceTable);
BR,
I have two tables, one called Season the other one Episode. Between them is a Link table that stores SeasonID and EpisodeID. How do I make sure that when a new episode is added the Link table will be updated as well?
Assuming that you are using SQL Service.
We can achieve with the help of trigger like this
Query
CREATE TRIGGER trig_Update_Episode
ON [Episode]
FOR INSERT
AS
Begin
IF NOT EXISTS (SELECT 1
FROM [dbo].[tblEpisodeSession] WITH (NOLOCK)
WHERE [EpisodeId] = [inserted.ID])
PRINT N'You must update an entry in tblSessionEpisode As well';
End
for both the table you should create a trigger like given above.
In example query you can replace message with your actual query which should actually create an entry in tblEpisodeSession.
Hope this helps.
I am currently using IN clause on a varchar field. Will using Contains of FTS help in performance?
For e.g.
Select * from Orders where City IN (‘London’ , ‘New York’)
vs
Select * from Orders where Contains (City, ‘London or New York’)
Thanks in advance.
Table Definition
CREATE TABLE Orders(ID INT PRIMARY KEY NOT NULL IDENTITY(1,1),City VARCHAR(100))
GO
INSERT INTO Orders
VALUES ('London'),('Newyork'),('Paris'),('Manchester')
,('Liverpool'),('Sheffield'),('Bolton')
GO
Create FTS on City Column using ID as the key
Used SSMS to create FTS Index.
Queries
-- Query 1
Select * from Orders
where City IN ('London' , 'NewYork')
GO
-- Query 2
Select * from Orders where
Contains (City, '"London" or "NewYork"')
GO
Execution Plans for both queries
As you can see The Query which used FTS costed 3 times more than the query which used IN Operator.
Having said this, when it comes to find Language specific terms in sql server FTS is the way to go, for example looking for Inflectional forms , Synonymous and much more Read Here for more information.
I have sqlite local database. I want to insert only fresh data from remote server to local database.Since there is no time field,it is difficult to insert only new records.How can i acheive this? I require this for my hybrid mobile app. Any helps apperciated..Thanks in advance.
Two tables:
my local db table is
tbl_orders
id name age
1 yyy 30
2 xxx 20
my remote db table is
tbl_orders
id name age
1 yyy 36
2 xxx 20
3 vvv 40
4 zzz 37
In the above the remote table contains additionally two records and also the value in first record(age column) get changed.now i want to insert and update this(i.e 1st,3rd,4th) to my local sqlite table without deleting and reinserting the whole table.
You should add a UNIQUE constrain in id.
Redefining your local table:
CREATE TABLE tbl_orders(UNIQUE id, name, age);
or without redefining table
CREATE UNIQUE INDEX tbl_orders_id ON tbl_orders(id);
With constrain, your updates become a single statement:
INSERT OR REPLACE INTO local.tbl_orders SELECT * FROM remote.tbl_orders;
Your table is replicated in two DB?
If yes, you can do an INSERT with NOT EXISTS clause in WHERE condition. Alternatively, add datetime field in your source table.
Another way:
Add a boolean field in your source DB (fl_sent), populated by a trigger when create a new row in your DB or update them. Default value is false, and when you want to syncronize your DBs your select is based on this field
SELECT * FROM myTable WHERE fl_sent = 0
For a more complete answer please post your tables.
EDIT AFTER COMMENT:
Solution 1:
Add field date in your remote table (source) (if you want, you write a trigger about toggle this field) and then execute your sendable query based on this date.
Solution 2:
Add field flag (fl_sent) set by zero (if you want, you write a trigger about toggle this field) and then execute your sendable query based on this flag.
I am very new to SQL and SQL server, would appreciate any help with the following problem.
I am trying to update a share price table with new prices.
The table has three columns: share code, date, price.
The share code + date = PK
As you can imagine, if you have thousands of share codes and 10 years' data for each, the table can get very big. So I have created a separate table called a share ID table, and use a share ID instead in the first table (I was reliably informed this would speed up the query, as searching by integer is faster than string).
So, to summarise, I have two tables as follows:
Table 1 = Share_code_ID (int), Date, Price
Table 2 = Share_code_ID (int), Share_name (string)
So let's say I want to update the table/s with today's price for share ZZZ. I need to:
Look for the Share_code_ID corresponding to 'ZZZ' in table 2
If it is found, update table 1 with the new price for that date, using the Share_code_ID I just found
If the Share_code_ID is not found, update both tables
Let's ignore for now how the Share_code_ID is generated for a new code, I'll worry about that later.
I'm trying to use a merge query loosely based on the following structure, but have no idea what I am doing:
MERGE INTO [Table 1]
USING (VALUES (1,23-May-2013,1000)) AS SOURCE (Share_code_ID,Date,Price)
{ SEEMS LIKE THERE SHOULD BE AN INNER JOIN HERE OR SOMETHING }
ON Table 2 = 'ZZZ'
WHEN MATCHED THEN UPDATE SET Table 1.Price = 1000
WHEN NOT MATCHED THEN INSERT { TO BOTH TABLES }
Any help would be appreciated.
http://msdn.microsoft.com/library/bb510625(v=sql.100).aspx
You use Table1 for target table and Table2 for source table
You want to do action, when given ID is not found in Table2 - in the source table
In the documentation, that you had read already, that corresponds to the clause
WHEN NOT MATCHED BY SOURCE ... THEN <merge_matched>
and the latter corresponds to
<merge_matched>::=
{ UPDATE SET <set_clause> | DELETE }
Ergo, you cannot insert into source-table there.
You could use triggers for auto-insertion, when you insert something in Table1, but that will not be able to insert proper Shared_Name - trigger just won't know it.
So you have two options i guess.
1) make T-SQL code block - look for Stored Procedures. I think there also is a construct to execute anonymous code block in MS SQ, like EXECUTE BLOCK command in Firebird SQL Server, but i don't know it for sure.
2) create updatable SQL VIEW, joining Table1 and Table2 to show last most current date, so that when you insert a row in this view the view's on-insert trigger would actually insert rows to both tables. And when you would update the data in the view, the on-update trigger would modify the data.