Hypertechblog

Types of SQL commands 1) DDL(data definition language) commands:       Used to create or change or delete any data base objects CREATE ALTER DROP TRUNCATE RENAME 2) DML(data manipulation language) COMMANDS       Used to fetch data / enter new data/ changing existed data / deleting the data from table. INSERT  UPDATE  DELETE  TRUNCATE 3) DRL(dataretrieval language) Command     SELECT (logicalcommand) 4) DCL(DATA CONTROL LANGUAGE) COMMANDS     Used to control the access of data base objects. These commands are used by DBA (databaseadministrator) GRANT  REVOKE 5) TCL(TRANSACTION CONTROL LANGUAGE) COMMANDS      Used to save or cancel the actions/transactions made on table data. COMMIT  ROLLBACK  SAVEPOINT

Bit fields are not portable . Because  bit fields cannot span machine words , and because the number of bits in a machine word is different on different machines, a particular program using bit fields might not even compile on a particular machine. Assuming that your program does compile, the order in which bits are assigned to bit fields is not defined. Therefore, different compilers, or even different versions of the same compiler, could produce code that would not work properly on data generated by compiled older code. Stay away from using bit fields, except in cases in which the machine can directly address bits in memory and the compiler can generate code to take advantage of it and the increase in speed to be gained would be essential to the operation of the program.