Oracle

Recently, a large volume of data in oracle tables needs to be deleted due to slow queries and updates. It is found that the query speed after deletion is still very slow. It turns out that the high watermark of delete oracle has not declined. In

An example is provided to illustrate the function of union all in the database. The present table Aid name1 name21 aa bb2 aa cc3 bb cc4 aa dd ................. www.2cto.com needs to count the number of times each name appears. The expected result is

In oracle, the single quotes in oralce are escaped. strings are referenced by single quotes, and the escape is also completed by single quotes. This is a headache for many beginners, especially those who are learning dynamic SQL. In simple single

How to view the execution plan in the Oracle client 1. run the "explain Plan" Syntax: SQL> Explain plan for www.2cto.com Try this command: SQL> explain plan for select * from mtl_system_items_ B where inventory_item_id = 149 and organization_id = 207

Restart the Oracle database command to restart the database (two database instances and listening services need to be started) execute the following command to require oracle users. If the current user is root, switch to the oracle user first. The

In relational databases, an index is a table-related database structure that enables faster execution of SQL statements corresponding to tables. The index function is equivalent to the book directory. You can quickly find the desired content based

Oracle role management overview roles are a classification management method for users, similar to the "create post authorization" that is often mentioned in business systems, users with different permissions can be divided into different roles. For

ORA-01810: format code appears twice (the to_date () function in Oralce is used to convert a string to a date object) The to_date () function in Oralce is used to convert a string to a date object, the specific format is to_date (string,

The not in problem in oracle has been busy recently. It's not a day or a night. I haven't had time to write a blog for a long time. Today, it's a very strange problem. It's been a long time since I had to write a blog. Www.2cto.com [SQL] select *

Oracle Aggregate functions --- percent_rank () and cume_dist () Specify the relative position of the grouping sequence PERCENT_RANK (expr [, expr]...) within group (order by expr [DESC | ASC] [NULLS {FIRST | LAST}] [, expr [DESC | ASC] [NULLS {FIRST

Oracle collection type description set type 1. usage conditions: a. data in a single row, using scalar variables. B. Single Row and multiple columns of data, usage record [For details, see: Click to open the link http://www.bkjia.com/database/201210/

High-efficiency optimization of Oracle SQL statements many people seem to know little about SQL optimization. Recently I have summarized several articles for your reference only. However, a few of them may depend on the situation, most of them are

The NVL, NVL2, NULLIF, and COALESCE functions in oracle are used to apply the string processing penalty, date functions, mathematical functions, and conversion functions previously introduced in Oracle. A type of function is a common function. The

In the use cases of partition and subpartition in super large tables, partition and subpartition are two common keywords in super large tables. They are mainly used for partitioning to improve data reading efficiency. (For more information about

Oracle Database role management 1. The super administrator creates the role myrole (a set of permissions) SQL> create role myrole; the role has been created. Www.2cto.com 2. grant the role myrole SQL> grant create session and create table to myrole

Oracle Database permission transfer 1. system permission transfer super administrator grants lisi the administrative permission to modify any table: SQL> grant alter any table to lisi with admin option; authorization successful. View system

Oracle and MySql functions for string truncation Oracle: 1. truncates the string before a character (excluding the character) in the string select Substr (P. SCHEDULE_CODE, 1, Instr (P. SCHEDULE_CODE, '(', 1)-1) from M_SUB_TASK_SCHEDULE_LOG P; 2.

Oracle Database migration may occur during the project, so the sequence may be reset, resulting in the current value of the sequence.When it is less than the maximum value of the field in the table that uses the sequence, an error occurs,

For plsql export table structure statements, select tools> export tables to export table structure and data tools> export user objects to export table structure www.2cto.com. You can use tools> export tables to use the intermediate SQL inserts page,

Oracle users cannot be deleted, and the system prompts "unable to delete connected users" 1. alter user XXX account lock; SELECT * from v $ session where username = 'lgdb'; alter system kill session 'xx, xx' drop user xx cascade 2. or shut down the