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).
Related
Is there a way in Access using SQL to get the difference between 2 tables?
I'm building an audit function and I want to return all records from table1 where a value (or values) doesn't match the corresponding record in table2. Primary keys will always match between the two tables. They will always contain the exact same number of fields, field names, and types, as each other. However, the number and name of those fields cannot be determined before the query is run.
Please also note, I am looking for an Access SQL solution. I know how to solve this with VBA.
Thanks,
There are several possibilities to compare fields with known names, but there is no way in SQL to access fields without knowing their name. Mostly becase SQL doesn't consider fields to have a specific order in a table.
So the only way to accomplish what you need in pure Access-SQL would be, if there was a SQL-Command for it (kind of like the * as placeholder for all fields). But there isn't. Microsoft Access SQL Reference.
What you COULD do is create an SQL-clause on the fly in VBA. (I know, you said you didn't want to do it in VBA - but this is doing it in SQL, but using VBA to create the SQL..).
Doing everything in VBA would probably take some time, but creating an SQL on the fly is very fast and you can optimize it to the specific table. Then executing the SQL is the fastest solution you can get.
Not sure without your table structure but you can probably get that done using NOT IN operator (OR) using WHERE NOT EXISTS like
select * from table1
where some_field not in (select some_other_field from table2);
(OR)
select * from table1 t1
where not exists (select 1 from table2 where some_other_field = t1.some_field);
SELECT A.*, B.* FROM A FULL JOIN B ON (A.C = B.C) WHERE A.C IS NULL OR B.C IS NULL;
IF you have tables A and B, both with colum C, here are the records, which are present in table A but not in B.To get all the differences with a single query, a full join must be used,like above
the question:
Find the title of the books whose keyword contains the last 3 characters of the bookgroup of the book which was booked by "Mr. Karim".
I am trying to do it like this:
SELECT Title
FROM Lib_Book
WHERE BookKeywords LIKE '%(SELECT BookGroup FROM Lib_Book WHERE BookId=(SELECT BookId from Lib_Booking, Lib_Borrower WHERE Lib_Booking.BId=Lib_Borrower.BId AND Lib_Borrower.BName = 'Mr. Karim'))%';
from the part after % upto the end returns me an answer which is 'programming'. so i need to indicate the BookKeyword as '%ing%'. How can i do that?
**the tables are huge so i hvnt written those here..if anyone need to those plz lemme know...thnx
You have the basic concept down, although it's not possible to process a SELECT statement inside a LIKE clause (and I'd probably shoot the RDBMS developer who allowed that - it's a GAPING HUGE HOLE for SQL Injection). Also, you're likely to have problems with multiple results, as your 'query' would fail the moment Mr. Karim had borrowed more than one book.
I'd probably start by attempting to make things run off of joins (oh, and never use implicit join syntax):
SELECT d.title
FROM Lib_Borrower as a
JOIN Lib_Booking as b
ON b.bId = a.bId
JOIN Lib_Book as c
ON c.bookId = b.bookId
JOIN Lib_Book as d
ON d.bookKeywords LIKE '%' + SUBSTRING(c.bookGroup, LENGTH(c.bookGroup) - 3) + '%'
WHERE a.bName = 'Mr. Karim'
Please note the following caveats:
This will get you all titles for all books with similar keywords to all borrowed books (from all 'Mr. Karim's). You may need to include some sort of restrictive criteria while joining to Lib_Booking.
The column bookKeywords seems potentially like a multi-value column (would need example data). If so, your table structure needs to be revised.
The use of SUBSTRING() or RIGHT() will invalidate the use of inidicies in joining to the bookGroup column. There isn't much you can necessarily do about that, given your requirements...
This table is not internationalization safe (because the bookGroup column is language-dependant parsed text). You may find yourself better served by creating a Book_Group table, a Keywords table, and a cross-reference Book_Keywords table, and joining on numerical ids. You may also want language-keyed Book_Group_Description and Keyword_Description tables. This will take more space, and probably take more processing time (increased number of joins, although potentially less textual processing), but give you increased flexibility and 'safety'.
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.
Is there a way I can search for a particular string value in a SQL SERVER 2005 database? I have this image path value that I want to modify and I think it's stored in the database.
Also - is there a way that I can search for a column's name for any table in a database? Likewise, search for a tables name in a database?
SELECT B.*
FROM information_schema.COLUMNS B
WHERE table_name
IN (SELECT A.TABLE_NAME FROM information_schema.Tables A WHERE TABLE_TYPE='BASE TABLE')
AND B.COLUMN_NAME LIKE '%yoursearchstring%'
Use this to get a list of all of the tables in a database.
SELECT *
FROM information_schema.Tables
Ust this to get a list of all of the columns in a table
SELECT column_name 'Column Name'
FROM information_schema.columns
WHERE table_name = MyTableName
You can use these together to search through every table and column to search for your string.
There may exist utilities which drill down the catalog/schema of a given server/database and use this info to search for a given match (or partial match) with a given pattern in all the text-like columns. You could possibly even write such a utility and introduce heuristics of your own (say not to search tables which have more than 10,000 rows because you expect the info to be a "configuration-type" table etc.)
An easier way may be to use SQL-Profiler to record every query sent to server (possibly filtered by IP address, by session id etc..). By then running the underlying application so that it would produce the particular string, you'll have a [hopefully] short list of queries, one of which targets the particular table / column where the path/string or parts therefore gets queried from.
Sometimes folks do this with dynamic sql to search across every column in the database. It won't perform all that well, but for a one-off search like this can be quite handy. A quick google search turned up this example - http://codesnippets.joyent.com/posts/show/2157
This is a pretty poor example since it queries each table N times where N is the number of columns (it should just do one table scan instead of N), but it might get the job done. You may also want to not limit to the first 100 chars like that example does.
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