slide môn học MySQL bài 4 implementing the SQL queries using MySQL II

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Implementing the SQL Queries using MySQL - II Session Review     MySQL list of databases in the server with the help of SHOW command The ALTER command enables us to modify the characteristics or attributes of a table or a database The SELECT command is used for data retrieval The DROP command is used to remove or delete a table from a database This command removes all data from that table along with the table definition from the database MySQL Database / Session / Slide of 18 Objectives      Work with keys Work with indexes Manipulate tables Control the output using ORDER BY clause Organize the output using the GROUP BY command MySQL Database / Session / Slide of 18 Working with Keys and Indexes - I      Indexes are used to improve the overall performance of a database Enables the searches on a database to be faster MySQL allows up to 32 indexes for each table Each index may consists up to 16 columns Advantages of indexing:    Searching is faster Sorting is faster Indexing causes the database to be slower process of altering MySQL Database / Session / Slide of 18 Working with Keys and Indexes - II   The syntax for creating an index for a table is: CREATE INDEX index_name ON tablename (column1,column2, , To create an index INDEX1 on columnN) EMP_DEPARTMENT, enter the following at the command prompt: CREATE INDEX INDEX1 ON EMP_DEPARTMENT(DATE_OF_JOI N); MySQL Database / Session / Slide of 18 Defining Keys - I     Keys are columns that helps to identify a record in a table Primary key is a unique identifier in a table Foreign key is a column in a table is a primary key in a different table In order to define a foreign key both the table must of the type InnoDB MySQL Database / Session / Slide of 18 Defining Keys - II  To add the foreign key, enter the following at the command prompt: ALTER TABLE EMP_SALARY ADD FOREIGN KEY (E_ID) REFERENCES EMP_DETAILS; MySQL Database / Session / Slide of 18 Manipulating the Tables   INSERT command is used to data in a table The command for the INSERT command is: INSERT [LOW_PRIORITY | DELAYED] [IGNORE] [INTO] tbl_name [(col_name, )] VALUES ({expression | DEFAULT}, ),( ), [ON DUPLICATE KEY UPDATE col_name = expression , ] MySQL Database / Session / Slide of 18 INSERT Command  To insert rows in EMP_DEPARTMENT, enter the following at the command prompt: INSERT INTO EMP_DEPARTMENT VALUES (101,’MARKETING’,’2000-05-15’,A01’); MySQL Database / Session / Slide of 18 UPDATE Command  The syntax for updating a table is: UPDATE [LOW_PRIORITY] [IGNORE] table SET column=value, [WHERE clause][LIMIT n]  To update a row in EMP_DETAILS table, enter the following at the command prompt: UPDATE EMP_DETAILS SET EMAIL_ID=’peter102@cbase com’WHERE E_ID=102; MySQL Database / Session / Slide 10 of 18 REPLACE Command  The syntax for deleting from a table is: REPLACE [DELAYED|LOW_PRIORITY] INTO table [(column,…)] VALUES (value, )  To update a row in EMP_DETAILS table, enter the following at the command prompt: REPLACE INTO EMP_DETAILS VALUES (106,’GEORGE’,’BLAIR’,’CALIF ORNIA’, 56474,’george106@cbase.com); MySQL Database / Session / Slide 11 of 18 DELETE Command   DELETE command is used to delete a row from a table Syntax for deleting from a table is: DELETE [LOW_PRIORITY|QUICK] FROM table [WHERE clause] [ORDER BY column, ] [LIMIT n]  To delete a row from the EMP_DETAILS table, enter the following at the command prompt: DELETE FROM EMP_DETAILS WHERE E_ID=106; MySQL Database / Session / Slide 12 of 18 Using the ORDER BY Clause – I    ORDER BY Clause is used to sort the table The syntax for 0RDER BY is: ORDER BY column [ASC|DESC] [,column2[ASC|DESC], ] If the ASC or DESC option is not specified then by default the output is sorted in the ascending order MySQL Database / Session / Slide 13 of 18 Using the ORDER BY Clause – II  To order the output DATE_OF _JOIN field in the ascending order, enter the following at the command prompt: SELECT * FROM EMP_DEPARTMENT ORDER BY DATE_OF_JOIN ASC; MySQL Database / Session / Slide 14 of 18 Using the GROUP BY Command - I   Grouping facilitates the user to group rows with similar values for a specific column into a single row in order to operate on them together The syntax for ordering is: GROUP BY column [,column2 ] MySQL Database / Session / Slide 15 of 18 Using the GROUP BY Command - II  To group the output of EMP_DEPARTMENT table on the DESIGNATION field, enter the following at the command prompt: SELECT * FROM EMP_DEPARTMENT GROUP BY DESIGNATION; MySQL Database / Session / Slide 16 of 18 Summary - I       Keys uniquely identify a record in a table Primary key is a unique identifier in a table Foreign key is a primary key in a different table We can define a primary key as well as foreign key while creating a table We also define these keys using the ALTER TABLE command INSERT command enables to add data in a table MySQL Database / Session / Slide 17 of 18 Summary - II      UPADTE command is used to modify data in a table REPALCE command is used to change data in a table DELETE command enables user to delete the data from a table ORBER BY option is used with the select command to order the output Grouping facilitates to group rows with similar values for a specific column into a single row MySQL Database / Session / Slide 18 of 18 [...]... sorted in the ascending order MySQL Database / Session 8 / Slide 13 of 18 Using the ORDER BY Clause – II  To order the output DATE_OF _JOIN field in the ascending order, enter the following at the command prompt: SELECT * FROM EMP_DEPARTMENT ORDER BY DATE_OF_JOIN ASC; MySQL Database / Session 8 / Slide 14 of 18 Using the GROUP BY Command - I   Grouping facilitates the user to group rows with similar... single row in order to operate on them together The syntax for ordering is: GROUP BY column [,column2 ] MySQL Database / Session 8 / Slide 15 of 18 Using the GROUP BY Command - II  To group the output of EMP_DEPARTMENT table on the DESIGNATION field, enter the following at the command prompt: SELECT * FROM EMP_DEPARTMENT GROUP BY DESIGNATION; MySQL Database / Session 8 / Slide 16 of 18 Summary - I  ... row from the EMP_DETAILS table, enter the following at the command prompt: DELETE FROM EMP_DETAILS WHERE E_ID=106; MySQL Database / Session 8 / Slide 12 of 18 Using the ORDER BY Clause – I    ORDER BY Clause is used to sort the table The syntax for 0RDER BY is: ORDER BY column [ASC|DESC] [,column2[ASC|DESC], ] If the ASC or DESC option is not specified then by default the output is sorted in the ascending... We also define these keys using the ALTER TABLE command INSERT command enables to add data in a table MySQL Database / Session 8 / Slide 17 of 18 Summary - II      UPADTE command is used to modify data in a table REPALCE command is used to change data in a table DELETE command enables user to delete the data from a table ORBER BY option is used with the select command to order the output Grouping...REPLACE Command  The syntax for deleting from a table is: REPLACE [DELAYED|LOW_PRIORITY] INTO table [(column,…)] VALUES (value, )  To update a row in EMP_DETAILS table, enter the following at the command prompt: REPLACE INTO EMP_DETAILS VALUES (106,’GEORGE’,’BLAIR’,’CALIF ORNIA’, 5 647 4,’george106@cbase.com); MySQL Database / Session 8 / Slide 11 of 18 DELETE Command   DELETE... delete the data from a table ORBER BY option is used with the select command to order the output Grouping facilitates to group rows with similar values for a specific column into a single row MySQL Database / Session 8 / Slide 18 of 18
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