If you want just a first selected row, you can: select fname from MyTbl where rownum = 1 You can also use analytic functions to order and take the top x: select max(fname) over (rank() order by some_factor) from MyTbl
The PARTITION BY clause sets the range of records that will be used for each “GROUP” within the OVER clause. In your example SQL, DEPT_COUNT will return the number of employees within that department for every employee record. (It is as if you’re de-nomalising the emp table; you still return every record in the emp … Read more
The PARTITION BY clause sets the range of records that will be used for each “GROUP” within the OVER clause. In your example SQL, DEPT_COUNT will return the number of employees within that department for every employee record. (It is as if you’re de-nomalising the emp table; you still return every record in the emp … Read more
http://download.oracle.com/docs/cd/B28359_01/java.111/b31224/urls.htm#BEIDHCBA Thin-style Service Name Syntax Thin-style service names are supported only by the JDBC Thin driver. The syntax is: @//host_name:port_number/service_name For example: jdbc:oracle:thin:scott/tiger@//myhost:1521/myservicename So I would try: jdbc:oracle:thin:@//oracle.hostserver2.mydomain.ca:1522/ABCD Also, per Robert Greathouse’s answer, you can also specify the TNS name in the JDBC URL as below: jdbc:oracle:thin:@(DESCRIPTION =(ADDRESS_LIST =(ADDRESS =(PROTOCOL=TCP)(HOST=blah.example.com)(PORT=1521)))(CONNECT_DATA=(SID=BLAHSID)(GLOBAL_NAME=BLAHSID.WORLD)(SERVER=DEDICATED)))
No! The same execution plan, look at these two tables: CREATE TABLE table1 ( id INT, name VARCHAR(20) ); CREATE TABLE table2 ( id INT, name VARCHAR(20) ); The execution plan for the query using the inner join: — with inner join EXPLAIN PLAN FOR SELECT * FROM table1 t1 INNER JOIN table2 t2 ON … Read more
For MySQL, use: DESCRIBE name_of_table; This also works for Oracle as long as you are using SQL*Plus, or Oracle’s SQL Developer.
Just use a where clause that won’t select any rows: create table xyz_new as select * from xyz where 1=0; Limitations The following things will not be copied to the new table: sequences triggers indexes some constraints may not be copied materialized view logs This also does not handle partitions
As for now, they are synonyms. VARCHAR is reserved by Oracle to support distinction between NULL and empty string in future, as ANSI standard prescribes. VARCHAR2 does not distinguish between a NULL and empty string, and never will. If you rely on empty string and NULL being the same thing, you should use VARCHAR2.
Aggregate the column by COUNT, then use a HAVING clause to find values that appear greater than one time. SELECT column_name, COUNT(column_name) FROM table_name GROUP BY column_name HAVING COUNT(column_name) > 1;
I had this issue and the fix was to make sure in tnsnames.ora the SERVICE_NAME is a valid service name in your database. To find out valid service names, you can use the following query in oracle: select value from v$parameter where name=”service_names” Once I updated tnsnames.ora to: TEST = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS … Read more