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部分 I. Database Relational

目錄

1. DB-Engines - DB-Engines Ranking
2. SysBench
3. SuperSmack
4. ETL (Extract-Transform-Load)
4.1. Kettle
4.2. suro
5. 數據遷移
5.1. Apache Sqoop
6. GreenSQL
7. Database design & E-R diagram
7.1. opensource database design tools
7.2. OpenSystemArchitect
7.3. SQL Power Architect
What are the difference between DDL, DML and DCL commands?
DDL is Data Definition Language statements. Some examples:
CREATE - to create objects in the database
ALTER - alters the structure of the database
DROP - delete objects from the database
TRUNCATE - remove all records from a table, including all spaces allocated for

the records are removed
COMMENT - add comments to the data dictionary
GRANT - gives user's access privileges to database
REVOKE - withdraw access privileges given with the GRANT command


DML is Data Manipulation Language statements. Some examples:
SELECT - retrieve data from the a database
INSERT - insert data into a table
UPDATE - updates existing data within a table
DELETE - deletes all records from a table, the space for the records remain
CALL - call a PL/SQL or Java subprogram
EXPLAIN PLAN - explain access path to data
LOCK TABLE - control concurrency


DCL is Data Control Language statements. Some examples:
COMMIT - save work done
SAVEPOINT - identify a point in a transaction to which you can later roll back
ROLLBACK - restore database to original since the last COMMIT
SET TRANSACTION - Change transaction options like what rollback segment to use