Oracle Sql Delete Example

SQL is the standard computer language used to access and process databases. What is SQL? SQL refers to Structured Query language SQL gives us the ability to access database SQL is an ANSI standard computer language editor Note: ANSI, United States national standardization Organization SQL What can you do? SQL database-oriented query SQL can retrieve data from a database SQL can insert new records in a database SQL updatable database can be deleted from the database SQL to delete records SQL can create New ...

Method 1 delete yourtable where [id] not in (select max ([id]) from yourtable group by (name + value) b on a.id = b.id where b.id ...

We want to do not only write SQL, but also to do a good performance of the SQL, the following for the author to learn, extract, and summarized part of the information to share with you! (1) Select the most efficient table name order (valid only in the Rule-based optimizer): The ORACLE parser processes the table names in the FROM clause in Right-to-left order, and the last table in the FROM clause (the underlying table driving tables) is processed first, In the case where multiple tables are included in the FROM clause, you must select the table with the least number of records as the underlying table. If...

The logical design of database is a very broad problem. In this paper, the main key design of the table is discussed in the design of MS SQL Server, and the corresponding solutions are given. Primary key design status and problems about database table primary key design, in general, based on business requirements, based on business logic, the formation of primary key. For example, when sales to record sales, generally need two tables, one is the summary description of the sales list, records such as sales number, the total amount of a class of cases, and the other table record of each commodity ...

SQL statement for querying and deleting duplicate records (i) For example, there is a field "name" in Table A, and the "name" value may be the same between different records, and now you need to query between the records in the table, the "name" value has duplicates, and select name, Count (*) from-a group by name has count (*) > 1 as ...

Database security Policy Database security issues have been around the database administrator's nightmare, the loss of database data and the database by illegal user intrusion makes the database administrator physically and mentally exhausted. This paper puts forward some security policies around the security of the database, hoping to help the database administrator, no longer nightmares every night. Database security issues should include two parts: first, the security of database data it should be able to ensure that when the database system downtime, when the database data storage media is corrupted and when the database user misoperation, database data ...

Logminer is an actual, useful analysis tool that Oracle has provided since 8i, which makes it easy to obtain specific content in Oracle Redo log files (archived log files), Logminer analysis tools are actually made up of a set of PL SQL package and a number of dynamic views that can be used to analyze online logs and archive logs to obtain a database of past detailed, specific operations, very useful. Why do you use Logminer? Mainly for the following reasons: When the database has been mistakenly operated, need not be completed ...

Logminer is an actual, useful analysis tool that Oracle has provided since 8i, which makes it easy to obtain specific content in Oracle Redo log files (archived log files), Logminer analysis tools are actually made up of a set of PL 　　SQL package and a number of dynamic views that can be used to analyze online logs and archive logs to obtain a database of past detailed, specific operations, very useful. 　　Why do you use Logminer? Mainly for the following reasons: When the database occurs ...

Through the introduction of the core Distributed File System HDFS, MapReduce processing process of the Hadoop distributed computing platform, as well as the Data Warehouse tool hive and the distributed database HBase, it covers all the technical cores of the Hadoop distributed platform. Through this stage research summary, from the internal mechanism angle detailed analysis, HDFS, MapReduce, Hbase, Hive is how to run, as well as based on the Hadoop Data Warehouse construction and the distributed database interior concrete realization. If there are deficiencies, follow-up ...

Through the introduction of the core Distributed File System HDFS, MapReduce processing process of the Hadoop distributed computing platform, as well as the Data Warehouse tool hive and the distributed database HBase, it covers all the technical cores of the Hadoop distributed platform. Through this stage research summary, from the internal mechanism angle detailed analysis, HDFS, MapReduce, Hbase, Hive is how to run, as well as based on the Hadoop Data Warehouse construction and the distributed database interior concrete realization. If there are deficiencies, follow-up and ...