Drop Table Command

Usually speaking of foreign keys, we only mention "the purpose of the foreign key is to determine the referential integrity of the data." However, what foreign keys specifically include the actions and meanings? 1, set the outer chain: (1), create a foreign key through create table: see 2 lines of code is built in the table command: create table city (... key idx_fk_country_id (country_id), constrain ...

MySQL command line is to learn the MySQL database must master the knowledge, here is to introduce you to 10 easy-to-use MySQL command line, I hope you learn MySQL command line can help. 1, the structure of the display data table: mysql> DESCRIBE table name; (DESC table name) 2, the establishment of data tables: mysql> USE library name; / / enter the database mysql> CREATE TABLE table name (field name VA ...

Hive in the official document of the query language has a very detailed description, please refer to: http://wiki.apache.org/hadoop/Hive/LanguageManual, most of the content of this article is translated from this page, Some of the things that need to be noted during the use process are added. Create tablecreate [EXTERNAL] TABLE [IF not EXISTS] table_name [col_name data_t ...

Http://www.aliyun.com/zixun/aggregation/13713.html ">hbase is a distributed, column-oriented open source database, rooted in a Google paper BigTable: A distributed storage system of structured data. HBase is an open-source implementation of Google BigTable, using Hadoop HDFs as its file storage system, using Hadoop mapreduce to handle ...

As long as you master the following method, you can basically get the mysql database. First, the connection MYSQL format: mysql-h host address-u username-p user password 1, Example 1: Connect to the local MySQL: First open the DOS window and then enter the directory mysqlbin, then type the command mysql -uroot - p, after the carriage return prompts you to lose the password, if you just installed MYSQL, super user root is no password, so enter directly into MYSQL, MYS ...

Since the installation has been installed well hypertable, the Iron strike experience hql. Prepare the experimental data. hadoop@hadoop:~$ gunzip access.tsv.gz hadoop@hadoop:~$ mv ACCESS.TSV ~/hypertable/0.9.2.5/examples/hql_ tutorial/hadoop@hadoop:~$ CD ~/hypertable/0 ....

The complete collection of SQL statement operations deserves to be permanently stored the following statements are part of the MSSQL statement and are not available in Access. SQL classification: ddl-data Definition language (create,alter,drop,declare) dml-Data Manipulation Language (Select,delete,update,insert) dcl-Data Control Language (Grant,revoke, Commit,rollback first, briefly introduce the basic statement: 1, Description: Create number ...

If a computer manufacturer, its database holds machine and accessories product information. The table used to save the whole product information is called pc; the table used to save the parts supply information is called parts. There is a field in the pc table, used to describe the type of CPU used in this computer; there is a field in the parts table, the description of the CPU model, we can think of it as a list of all CPU models. Obviously, the CPU used by this manufacturer must be a model that exists in the supply information sheet. At this time, two tables ...

1.1: Increase the secondary data file from SQL SERVER 2005, the database does not default to generate NDF data files, generally have a main data file (MDF) is enough, but some large databases, because of information, and query frequently, so in order to improve the speed of query, You can store some of the records in a table or some of the tables in a different data file. Because the CPU and memory speed is much larger than the hard disk read and write speed, so you can put different data files on different physical hard drive, so that the execution of the query, ...

One, the required installation package apache_1.3.19.tar.gz php-4.0.4.tar.gz mysql-3.23.32.tar.gz Note: The above are source code instead of RPM Package II, Software Installation 1. Install MySQL (1) Unlock the compressed package cd/usr/localtar-zvxf mysql-3.23.32.tar.gz (2) will produce mysql-3.23.32 directory to/usr/local/mys ...