May be this question is redundant but I am posting it as I could not get an exact solution (Please read Actual Scenario).
I have the following script which returns all the tables and corresponding no. of rows.
SELECT
sysobjects.Name, sysindexes.Rows
FROM
sysobjects
INNER JOIN sysindexes
ON sysobjects.id = sysindexes.id
WHERE
type = 'U'
AND sysindexes.IndId < 2 ORDER BY ([Rows])
Now, I want to join this result set with similar result set on a different database (with same structure). I am not able to use four partition naming with sysobjects. It gives error: The multi-part identifier "My_Database1.sysobjects.Name" could not be bound.
Actual Scenario: I have a duplicate database and want to know in which tables data has not been moved from original database.
Any alternate solution would also help.
put .dbo between "My_Database1. and sysobjects.Name" as in
My_Database1.dbo.sysobjects
you should be ble to query sys tables on different database than the one you are connected (as long as they are on the same instance, of course). Check your sysntax, I believe you are missing the schema name sys so it would be:
SELECT * FROM My_Database1.sys.sysobjects
Please use sys object for system data table:
select sys_obj.* from DatabaseName.Sys.sysobjects sys_obj
Related
I want to get Informix database table information and column information such as
table names
column names of the table
data types of the columns
data type length (ex: if column is varchar)
constraints on the columns
I am able to find the table names and column names using this query to get the table names:
select tabname from systables
to find the column name
SELECT TRIM(c.colname) AS table_dot_column
FROM "informix".systables AS t, "informix".syscolumns AS c
WHERE t.tabname = 'agent_status'
AND t.tabtype = 'T'
and t.tabid = c.tabid
AND t.tabid >= 100 ;
but I am not able to find the data types and constraints on the columns.
Can anyone tell me the SQL query to get the total details of the table mentioned above?
Wow! That's a complex query - best treated as at least two, probably three queries; or maybe that's what you had in mind anyway.
You might want to select tabid and owner in the first query, and it is good form to use "informix".systables rather than just systables (though that only really matters in a MODE ANSI database, but then it really does matter).
The query on syscolumns is fine, though the t.tabid >= 100 clause is probably redundant, unless you definitively want to prevent people learning about the columns in system catalog tables. Also, it can be helpful to know about the columns in a view, so the tabtype = 'T' might be too stringent.
Decoding the data types is fiddly. For the built-in types, it is not too difficult; for user defined types, it is considerably harder work. The coltype and collength (and extended_d) tell you about the type. You can find C code to translate the basic types in my SQLCMD package, in sqltypes.ec. You can find some simple SQL (that may not be complete) in $INFORMIXDIR/etc/xpg4_is.sql.
Constraint information is stored in sysconstraints and related tables. You can find code for some constraints in the SQLCMD source already mentioned (file sqlinfo.ec).
Give a database (Sybase) with many tables, I would like to write a SQL query that will calculate, for each table, the number of rows and the number of columns.
Unfortunately, my SQL is a bit rusty. I can generate the table names:
select name from sysobjects where type = 'U'
but how to bind the databases returned to T in:
select count(*) from T
is beyond me. Is it even possible to do this kind of thing?
I don't use Sybase, but the online docs indicate the row counts are in systabstats and the columns are in syscolumns.
SELECT sysobjects.name,
(SELECT COUNT(*) FROM syscolumns WHERE syscolumns.id = sysobjects.id) AS cols,
systabstats.rowcnt
FROM sysobjects
JOIN systabstats
ON (sysobjects.id = systabstats.id AND sysobjects.type = 'U' AND systabstats.indid = 0)
As fredt has given the answer, I'll just provide some extra info.
The built in procedure sp_spaceused "tablename" will give you the number of rows for a selected table, along with details of how much storage space it's using. Used without the parameter it provides storage usage for the current database as a whole.
You can look at the SQL in the various system stored procedures to see where they get their information from. sp_spaceused and sp_help would both be useful for you in this. They live in the sybsystemprocs database. Just be careful not to modify any of those procedures.
There are various versions of a stored procedure called sp_rowcount floating around the internet, that provide what you ask for (rowcount anyway), but inside they are equivalent to the select statement from fredt. The one I use provides index count and table locking scheme. I don't recall exactly where I got mine so don't want to just distribute it in case I upset someone's copyright.
Morning,
I have a stored procedure that returns 'SELECT *' from a table.
Whenever I add a new column to the table, the 'SELECT *' often returns some data in the wrong columns.
Is this an optimization or caching problem? How do I solve this without having to explicitly define the return column names in my stored procedure?
Thanks!
Regardless of the exact nature of your problem, or a solution to it, I would recommend that you don't use Select * From Table. This is less efficient - each time you run the query, an extra request is sent to the DB to determine exactly what columns '*' constitutes, and then a proper request is sent with specific column information.
The reason for your problem probably depends on the client stack you're using.
Speaking in very general terms, SQL Server will return the columns in the order they're added to the table if you perform a SELECT *. If there is more than one table involved in the query, it will return the columns from each table in the order they appear in the query.
Neither caching nor optimisation should affect this server-side if the table columns have changed, so it may be something happening between your code and the server, in whatever data access stack you happen to be using.
This is one of the reasons it's generally recommended not to use "SELECT *" in client code.
The best way to avoid this problem is to have the stored procedure return a predefined set of columns (SELECT a, b instead of SELECT *) and use a table join to retrieve the rest of the code. Because stored procedures cannot be part of a query, you could refactor the stored procedure into a table-valued user-defined function and perform a join on it:
SELECT f.a, f.b, t.*
FROM dbo.fn_YourFunction('a', 'b') f
INNER JOIN YourTable t ON f.id = t.id
Ok, here is my dilemma I have a database set up with about 5 tables all with the exact same data structure. The data is separated in this manner for localization purposes and to split up a total of about 4.5 million records.
A majority of the time only one table is needed and all is well. However, sometimes data is needed from 2 or more of the tables and it needs to be sorted by a user defined column. This is where I am having problems.
data columns:
id, band_name, song_name, album_name, genre
MySQL statment:
SELECT * from us_music, de_music where `genre` = 'punk'
MySQL spits out this error:
#1052 - Column 'genre' in where clause is ambiguous
Obviously, I am doing this wrong. Anyone care to shed some light on this for me?
I think you're looking for the UNION clause, a la
(SELECT * from us_music where `genre` = 'punk')
UNION
(SELECT * from de_music where `genre` = 'punk')
It sounds like you'd be happer with a single table. The five having the same schema, and sometimes needing to be presented as if they came from one table point to putting it all in one table.
Add a new column which can be used to distinguish among the five languages (I'm assuming it's language that is different among the tables since you said it was for localization). Don't worry about having 4.5 million records. Any real database can handle that size no problem. Add the correct indexes, and you'll have no trouble dealing with them as a single table.
Any of the above answers are valid, or an alternative way is to expand the table name to include the database name as well - eg:
SELECT * from us_music, de_music where `us_music.genre` = 'punk' AND `de_music.genre` = 'punk'
The column is ambiguous because it appears in both tables you would need to specify the where (or sort) field fully such as us_music.genre or de_music.genre but you'd usually specify two tables if you were then going to join them together in some fashion. The structure your dealing with is occasionally referred to as a partitioned table although it's usually done to separate the dataset into distinct files as well rather than to just split the dataset arbitrarily. If you're in charge of the database structure and there's no good reason to partition the data then I'd build one big table with an extra "origin" field that contains a country code but you're probably doing it for legitimate performance reason.
Either use a union to join the tables you're interested in http://dev.mysql.com/doc/refman/5.0/en/union.html or by using the Merge database engine http://dev.mysql.com/doc/refman/5.1/en/merge-storage-engine.html.
Your original attempt to span both tables creates an implicit JOIN. This is frowned upon by most experienced SQL programmers because it separates the tables to be combined with the condition of how.
The UNION is a good solution for the tables as they are, but there should be no reason they can't be put into the one table with decent indexing. I've seen adding the correct index to a large table increase query speed by three orders of magnitude.
The union statement cause a deal time in huge data. It is good to perform the select in 2 steps:
select the id
then select the main table with it
I am attempting to provide a general solution for the migration of data from one schema version to another. A problem arises when the column data type from the source schema does not match that of the destination. I would like to create a query that will perform a preliminary compare on the columns data types to return which columns need to be fixed before migration is possible.
My current approach is to return the table and column names from information_schema.columns where DATA_TYPE's between catalogs do not match. However, querying information_schema directly will only return results from the catalog of the connection.
Has anyone written a query like this?
I do this by querying the system tables directly. Look into the syscolumns and sysobjects tables. You can also join across linked servers too
select t1.name as tname,c1.name as cname
from adventureworks.dbo.syscolumns c1
join adventureworks.dbo.sysobjects t1 on c1.id = t1.id
where t1.type = 'U'
order by t1.name,c1.colorder
I have always been in the fortunate position to have Red Gate Schema compare which i think would do what you ask. Cheap at twice the price!