Lesson 05: How to Insert, Update, and Delete Data. By S. Sabraz Nawaz Senior Lecturer in MIT FMC, SEUSL

Transcription

1 Lesson 05: How to Insert, Update, and Delete Data By S. Sabraz Nawaz Senior Lecturer in MIT FMC, SEUSL

2 The syntax of the INSERT statement INSERT [INTO] table_name [(column_list)] [DEFAULT] VALUES (expression_1 [, expression_2]...) [, (expression_1 [, expression_2]...)...] How to insert a single row into a table You use the INSERT statement to add a new row to a table. In the INSERT clause, you specify the name of the table that you want to add a row to, along with an optional column list. You specify the values to be inserted in the VALUES clause. The values you specify depend on whether you include a column list. If you don t include a column list: You must code a value for every column, in the same order as they appear in the table. The only exception is an identity column, which must be omitted. Slide 2

3 How to insert a single row into a table (continued) If you include a column list: You must specify the column values in the same order as they appear in the column list. You can omit columns with default values and columns that accept null values, and you must omit identity columns. To insert a null value into a column, you can use the NULL keyword. To insert a default value into a column, you can use the DEFAULT keyword. If all of the table columns are identity columns, columns with default values, or columns that allow null values, you can code the DEFAULT keyword at the beginning of the VALUES clause and then omit the list of values. Slide 3

4 The values for a new row in the Invoices table Column Value Column Value InvoiceID (Next available unique ID) PaymentTotal 0 VendorID 97 CreditTotal 0 InvoiceNumber TermsID 1 InvoiceDate InvoiceDueDate InvoiceTotal 8, PaymentDate null Slide 4

5 An INSERT statement that adds the new row without using a column list INSERT INTO InvoiceCopy VALUES (97, '456789', ' ', , 0, 0, 1, ' ', NULL) An INSERT statement that adds the new row using a column list INSERT INTO InvoiceCopy (VendorID, InvoiceNumber, InvoiceTotal, PaymentTotal, CreditTotal, TermsID, InvoiceDate, InvoiceDueDate) VALUES (97, '456789', , 0, 0, 1, ' ', ' ') The response from the system (1 row(s) affected) Slide 5

6 An INSERT statement that adds three new rows INSERT INTO InvoiceCopy VALUES (95, ' ', ' ', , 0, 0, 1, ' ', NULL), (102, '109596', ' ', 22.97, 0, 0, 1, ' ', NULL), (72, '40319', ' ', , 0, 0, 1, ' ', NULL) The response from the system (3 row(s) affected) Slide 6

7 Working with Update Statements Slide 7

8 The syntax of the UPDATE statement UPDATE table_name SET column_name_1 = expression_1 [, column_name_2 = expression_2]... [FROM table_source [[AS] table_alias] [WHERE search_condition] How to perform a basic update operation You use the UPDATE statement to modify one or more rows in the table named in the UPDATE clause. You name the columns to be modified and the value to be assigned to each column in the SET clause. You can specify the value for a column by using a literal, an expression, or the DEFAULT or NULL keyword when appropriate. Warning: If you omit the WHERE clause, all the rows in the table will be updated. Slide 8

9 An UPDATE statement that assigns new values to two columns of one row in the InvoiceCopy table UPDATE InvoiceCopy SET PaymentDate = ' ', PaymentTotal = WHERE InvoiceNumber = '97/522' (1 row(s) affected) An UPDATE statement that assigns a new value to one column of all the invoices for a vendor UPDATE InvoiceCopy SET TermsID = 1 WHERE VendorID = 95 (6 row(s) affected) An UPDATE statement that uses an arithmetic expression to assign a value to a column UPDATE InvoiceCopy SET CreditTotal = CreditTotal WHERE InvoiceNumber = '97/522' (1 row(s) affected) Slide 9

10 Working with Delete Statement Slide 10

11 The syntax of the DELETE statement DELETE [FROM] table_name [FROM table_source] [WHERE search_condition] How to perform a basic delete operation You can use the DELETE statement to delete one or more rows from the table you name in the DELETE clause. You specify the conditions that must be met for a row to be deleted in the WHERE clause. You can specify additional criteria for the delete operation in the FROM clause. Warning: If you omit the WHERE clause, all the rows in the table will be deleted. Slide 11

12 A DELETE statement that removes a single row from the InvoiceCopy table DELETE InvoiceCopy WHERE InvoiceID = 115 (1 row(s) affected) A DELETE statement that removes all the invoices for a vendor DELETE InvoiceCopy WHERE VendorID = 37 (3 row(s) affected) A DELETE statement that removes all the rows from the InvoiceCopy table DELETE InvoiceCopy (114 row(s) affected) Slide 12

13 Thank You