I am migrating data from MS SQL to Netezza and so I need to find the row counts of all tables in a database (in Netezza). Any query for the same would be of an immense help to me as I'm completely new to this. Thanks in advance.
This query does it directly from _v_table:
SELECT TABLENAME, RELTUPLES FROM _V_TABLE where objtype = 'TABLE' ORDER BY RELTUPLES
something like this should work:
select 'select '||chr(39)||tablename||chr(39)||' as entity, count(1) from '||tablename||' union all'
from _v_table
where object_type ='TABLE';
copy/paste the result, remove the last "union all".
I have never used Netezza but googled and found:
http://www.folkstalk.com/2009/12/netezza-count-analytic-functions.html
SELECT dept_id,
salary,
COUNT(1) OVER() total_cnt
FROM Employees
If you don't know what tables that exists:
http://www.folkstalk.com/2009/11/netezza-system-catalog-views.html
select * from _v_table;
Another way to acquire the row counts for a table (if you have access to the operating system level) is to use the Netezza nz_get_table_rowcount command. You can enter, "nz_get_table_rowcount -h" to get all of the help text on this command, but the format is:
Usage: nz_get_table_rowcount [database]
Purpose: Perform a "SELECT COUNT(*) FROM ;" to get its true rowcount.
Thus, this script results in a full table scan being performed.
Inputs: The database name is optional. If not specified, then $NZ_DATABASE
will be used instead.
The table name is required. If only one argument is specified, it
will be taken as the table name.
If two arguments are specified, the first will be taken as the
database name and the second will be taken as the table name.
Outputs: The table rowcount is returned.
Use this command in a shell script to cycle through all of the tables within a database. Use nz_get_table_names to get the list of tables within a database.
Related
Is it possible to get table name in select statement?
Example:
SELECT Id, "Users" as TableName
FROM Users
I don't want to write "Users" manually but to determine it based on FROM statement.
I'm doing some migrations from one database to another (with different structure), and I have mapping table that stores old table names so that's why I need this (it's less error prone).
You can use following sub-query to get this information (works on SQL Server 2012+):
SELECT *,
(select object_name(ind.object_id)
from sys.fn_PhysLocCracker(%%physloc%%) plc
INNER JOIN SYS.DM_DB_DATABASE_PAGE_ALLOCATIONS(DB_ID(),null,null,null,null) ind
ON ind.allocated_page_file_id = plc.file_id
AND ind.allocated_page_page_id = plc.page_id) as table_name
FROM [your table]
It is painfully slow, caching on the side page allocation will speed things up.
Alternatively, if you want to do it for all tables, you can use following stored procedure:
USE [DB_NAME]
EXEC sp_msforeachtable 'SELECT Id, ''?'' AS [TableName] FROM ?'
Maybe it will be helpful for somebody :)
I am attempting query my oracle database to determine the number of entries in each table. I spooled the result of the following query to a sql file :
select 'select count(*) '||table_name||';' from dba_tables;
This created a sql file of the format
select count(*) from Table_Name1;
select count(*) from Table_Name2;
etc
I then spooled the output of running this sql file, however it only returned a count for some of the tables, for other tables it simply says:
'This table or view does not exist'
How can that be if I've just populated that list of table names automatically from the database?
The end aim of this exercise is to have a file with the number of all fields in each table, then make a change to the program using this database and run the same operation again into a new file and compare the 2 so that I can see which tables change when I make a change to the program.
You forgot to fully qualify the names:
select 'select count(*) '||owner||'.'||table_name||';'
from dba_tables;
In case you have tables that have non-standard names, you should throw double quotes in there as well:
select 'select count(*) "'||owner||'"."'||table_name||'";'
from dba_tables;
How can I select the column name and table name from a SQL?
I tried something like this but it didn't work:
select column_name, table_name from (select * from users);
This might sound silly, but I have a list of different SQLs and I need to extract their columns and tables into a list. So some of the statements could me:
select username, password from users
select createdate from userlog
select * from dept
...
If I can select the column name and table name of a select statement, then I should get, say for the first statement, username and password for columns and users for table name. And createdate for column and userlog for table name in the second statement.
Then if it all works, I can then loop through the list of select statements and extract their column and table names.
The below query worked for Oracle database.
SELECT COLUMN_NAME,TABLE_NAME FROM ALL_TAB_COLUMNS
You can see more about information-schema
Edit:
You may try like this:
SELECT COLUMN_NAME,TABLE_NAME FROM ALL_TAB_COLUMNS
WHERE TABLE_NAME IN (SELECT ColumnName FROM users)
You need to parse the SQL statement so the SQL engine figures out the columns and datatypes of the columns that the statement returns.
How you do it best depends on what environment you are using. In some programming languages when you create a SqlPreparedStatement or OraCommand or whatever the object may be called, that object may have a metadata collection populated with column information after parsing.
If you are doing it in the database itself, parsing your statement with DBMS_SQL can get you the information you need. See Example 8 in the documentation at this link:
http://docs.oracle.com/database/121/ARPLS/d_sql.htm#ARPLS68205
--
Oh, and this gives you column names of the select statement. The table names I do not know of any way to get easily.
I'm going through all tables in a database trying to determine which tables are old (have not been altered in a long time). I've been going through and flagging all tables with old DTS's as "old"
Is there a more efficient way to do this? Can I run a statement that scans all tables in a database for date-timestamp fields and then looks at the most recent ones?
Thank you in advance for any help you can provide!
You can use the INFORMATION_SCHEMA.COLUMNS view to retrieve all the tables having the timestamp column (assuming the column name is known and not used for other columns).
Use these to generate Dynamic SQL of the form
SELECT COUNT(*) ,#TableName FROM #TableName WHERE #TimeStampColumn < #TimestampToCheck
The tables where count(*) is 0 are the ones you need to look at
I would do something like this:
Show a COUNT(*) of rows written in the last year... if you get 0, you know the table isn't in use.
Use the information_schema to get the columns/tables.
SELECT 'SELECT COUNT(*) AS ['+TABLE_NAME+'] FROM ['+TABLE_CATALOG+'].['+TABLE_SCHEMA+'].['+TABLE_NAME+'] WHERE '+COLUMN_NAME+' > DATEADD(YY,-1,CONVERT(DATETIME,FLOOR(CONVERT(FLOAT,GETDATE()))))'
-- SELECT *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE DATA_TYPE='DATETIME'
--AND (COLUMN_DEFAULT='(getdate())' OR COLUMN_DEFAULT='CURRENT_TIMESTAMP')
You can add the last line in, if you only want columns with a default value.
Then take the output, copy to a new window, and run it!
I'm using Oracle DB and I would like to write a SQL query that I could then call with JDBC. I'm not very familiar with SQL so if someone can help me, that could be great ! Here is the problem. I have a table MY_TABLE wich contains a list of another tables, and I would like to keep only the nonempty tables and those that their names start by a particular string.
The query I wrote is the following :
select TABLE_NAME
from MY_TABLE
where TABLE_NAME like '%myString%'
and (select count(*) from TABLE_NAME where rownum=1)<>0
order by TABLE_NAME;`
The problem comes from the second SELECT, but I don't know how can I do to use the TABLE_NAME value.
Does someone have an idea ?
Thanks.
[Added from comments]
Actually, I need to test the V$ views contained in the ALL_CATALOG table. But if I can find another table where all these views are contained too and with a NUM_ROWS column too, it would be perfect !
Standard versions of SQL do not allow you to replace 'structural elements' of the query, such as table name or column name, with variable values or place-holders.
There are a few ways to approach this.
Generate a separate SQL statement for each table name listed in MY_TABLE, and execute each in turn. Brute force, but effective.
Interrogate the system catalog directly.
Investigate whether there are JDBC metadata operations that allow you to find out about the number of rows in a table without being tied to the system catalog of the specific DBMS you are using.
Can you use oracle view USER_TABLES? then query will be much easier
select TABLE_NAME
from USER_TABLES
where TABLE_NAME like '%myString%'
and Num_ROWS > 0
order by TABLE_NAME;`