I have the schema HR and USER A and ran the following query
**select count(*) from emp_table**
Upon running this query no data was returned but the table has data but if i run the query like this
**select count(*) from hr.emp_table**
then the data is returned.
Thanks
Just check from which database you connected..may be you are connected to wrong database table which doesnt has any data..
As you mentioned the below query clearly suggest that you have table emp_table in hr database which has data:
select count(*) from hr.emp_table
To verify which database you are connected use below query :
select name from v$database;
OR
SELECT username, machine, program
FROM v$session
WHERE type = 'USER';
As your first SQL did not throw any error,Your current schema (Not HR) has emp_table table having no data.
When you use HR.emp_table, it is refereeing your emp_table of HR schema.
So it is always good to prefix schema name with table name.
Related
my query just runs and doesnt execute, what is wrong. work on oracle sql developer, company server
CREATE TABLE voice2020 AS
SELECT
to_char(SDATE , 'YYYYMM') as month,
MSISDN,
SUM(CH_MONEY_SUBS_DED)/100 AS AIRTIME_VOICE,
SUM(CALLDURATION/60) AS MIN_USAGE,
sum(DUR_ONNET_OOB/60) as DUR_ONNET_OOB,
sum(DUR_ONNET_IB/60) as DUR_ONNET_IB,
sum(DUR_ONNET_FREE/60) as DUR_ONNET_FREE,
sum(DUR_OFFNET_OOB/60) as DUR_OFFNET_OOB,
sum(DUR_OFFNET_IB/60) as DUR_OFFNET_IB,
sum(DUR_OFFNET_FREE/60) as DUR_OFFNET_FREE,
SUM(case when sdate < to_date('20190301','YYYYMMDD')
then CH_MONEY_PAID_DED-nvl(CH_MONEY_SUBS_DED,0)-REV_VOICE_INT-REV_VOICE_ROAM_OUTGOING-REV_VOICE_ROAM_Incoming
else (CH_MONEY_OOB-REV_VOICE_INT-REV_VOICE_ROAM_OUTGOING-REV_VOICE_ROAM_Incoming) end)/100 AS VOICE_OOB_SPEND
FROM CCN.CCN_VOICE_MSISDN_MM#xdr1
where MSISDN IN ( SELECT MSISDN FROM saayma_a.BASE30112020) --change date
GROUP BY
MSISDN,
to_char(SDATE , 'YYYYMM')
;
This is a performance issue. Clearly the query driving your CREATE TABLE statement is taking too long to return a result set.
You are querying from a table in a remote database (CCN.CCN_VOICE_MSISDN_MM#xdr1) and then filtering against a local table (saayma_a.BASE30112020) . This means you are going to copy all of that remote table across the network, then discard the records which don't match the WHERE clause.
You know your data (or at least you should know it): does that sound efficient? If you're actually discarding most of the records you should try to filter CCN_VOICE_MSIDN_MM in the remote database.
If you need more advice you need to provide more information. Please read this post about asking Oracle tuning questions on this site, then edit your question to include some details.
You are executing CTAS (CREATE TABLE AS SELECT) and the purpose of this query is to create the table with data which is generated via this query.
If you want to just execute the query and see the data then remove first line of your query.
-- CREATE TABLE voice2020 AS
SELECT
.....
Also, the data of your actual query must be present in the voice2020 table if you have already executed it once.
Select * from voice2020;
Looks like you are trying to copying the data from one table to another table, Can you once create the table if it's not created and then try this statement.
insert into target_table select * from source_table;
I have a column name "CustomerIDClass" and I need to find the table it's associated with within an entire Oracle database.
I've run this to determine the owner and name of the table where this column name appears:
select * from DBA_TAB_COLUMNS
where COLUMN_NAME LIKE '%CustomerIDClass%';
and I'm getting this response:
I don't have enough reputation to post the image, so here's the link: http://i.imgur.com/a7rcKoA.png
I have no idea how to access this (BIN$Csew==) table. When I try to use it as a table name I get errors or messages saying that no rows were returned.
My main goal here is to write a simple statement that lets me search the database for the "CustomerIDClass" and view the table that contains this column name.
This table is in the recycle bin. You have to issue FLASHBACK TABLE "Customer1"."BIN$Csew==$0" TO BEFORE DROP command, given you have the appropriate privileges.
Doc: http://docs.oracle.com/cd/B19306_01/server.102/b14200/statements_9012.htm
Do note that in oracle the column names are stored in capital but you are using mixed case in your like statement therefore the select clause will not return any result
Try the below
select * from DBA_TAB_COLUMNS
where COLUMN_NAME LIKE '%CUSTOMERIDCLASS%';
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 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.
I am connected to a oracle database with a read only user and i used service name while Setting up connection in sql developer hence i dont know SID ( schema ).
How can i find out schema name which i am connected to ?
I am looking for this because i want to generate ER diagram and in that process at one step it asks to select schema. When i tried to select my user name , i dint get any tables as i guess all tables are mapped with schema user.
Edit: I got my answer partially by the below sql Frank provided in comment , it gave me owner name which is schema in my case. But I am not sure if it is generic solution applicable for all cases.
select owner, table_name from all_tables.
Edit: I think above sql is correct solution in all cases because schema is owner of all db objects. So either i get schema or owner both are same. Earlier my understanding about schema was not correct and i gone through another question and found schema is also a user.
Frank/a_horse_with_no_name Put this in answer so that i can accept it.
Call SYS_CONTEXT to get the current schema. From Ask Tom "How to get current schema:
select sys_context( 'userenv', 'current_schema' ) from dual;
To create a read-only user, you have to setup a different user than the one owning the tables you want to access.
If you just create the user and grant SELECT permission to the read-only user, you'll need to prepend the schema name to each table name. To avoid this, you have basically two options:
Set the current schema in your session:
ALTER SESSION SET CURRENT_SCHEMA=XYZ
Create synonyms for all tables:
CREATE SYNONYM READER_USER.TABLE1 FOR XYZ.TABLE1
So if you haven't been told the name of the owner schema, you basically have three options. The last one should always work:
Query the current schema setting:
SELECT SYS_CONTEXT('USERENV','CURRENT_SCHEMA') FROM DUAL
List your synonyms:
SELECT * FROM ALL_SYNONYMS WHERE OWNER = USER
Investigate all tables (with the exception of the some well-known standard schemas):
SELECT * FROM ALL_TABLES WHERE OWNER NOT IN ('SYS', 'SYSTEM', 'CTXSYS', 'MDSYS');
How about the following 3 statements?
-- change to your schema
ALTER SESSION SET CURRENT_SCHEMA=yourSchemaName;
-- check current schema
SELECT SYS_CONTEXT('USERENV','CURRENT_SCHEMA') FROM DUAL;
-- generate drop table statements
SELECT 'drop table ', table_name, 'cascade constraints;' FROM ALL_TABLES WHERE OWNER = 'yourSchemaName';
COPY the RESULT and PASTE and RUN.