COSC 304 Lab 5 Week of October 22, 2018

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1 COSC 304 Lab 5 Week of October 22, 2018 Objectives: Working with Functions Due 30 minutes before your lab period in two weeks (Week of November 5) Use string manipulation functions LENGTH(), UPPER(), LOWER(), SUBSTR(), INSTR(), CONCAT() Test for NULL using NVL() Use date related functions TO_DATE(), TO_CHAR() Solve problems with DECODE() String Manipulation This section will introduce you to several Oracle functions that will allow you to manipulate strings. Length Function LENGTH() The LENGTH() function in Oracle returns the length (in number of characters) of a string. Here is its syntax: LENGTH(sourceString) sourcestring the string from which the length will be obtained Return value: an integer which is the number of characters in sourcestring. Uppercase and Lowercase Functions UPPER() and LOWER() The UPPER() and LOWER() functions in Oracle return a new string that matches the parameter string where the alphabetic characters of the parameter string are replaced with uppercase and lowercase characters respectively. Here are their syntaxes: UPPER(sourceString) LOWER(sourceString) sourcestring the string from which the return string will be built Return value: a new string that matches sourcestring with its alphabetic characters replaced with uppercase (UPPER()) or lowercase (LOWER()) letters. COSC 304 Lab Assignment 5 Page 1

2 Substring Function SUBSTR() The SUBSTR() function in Oracle works much like the substring functions you have used in programming languages like Java. Here is its syntax: SUBSTR(sourceString, startposition, [len]) sourcestring the string from which the substring will be obtained startposition the point at which to start the substring len an optional parameter that indicates the number of characters in the substring Return value: the substring of length, len, starting at character startposition location within sourcestring. If no len parameter is specified, the end of the substring will be the end of the source string. Note that characters start counting from 1 (not zero) Examples: SUBSTR('Hello World!', 1, 5) returns Hello SUBSTR('Hello World!', 3, 5) returns llo W SUBSTR('Hello World!', 7, 3) returns Wor SUBSTR('Hello World!', 7) returns World! SUBSTR('Hello World!', 15) returns null Try running each of the above examples using the system table DUAL: SELECT SUBSTR('Hello World!', 1, 5) FROM DUAL; SELECT SUBSTR('Hello World!', 3, 5) FROM DUAL; SELECT SUBSTR('Hello World!', 7, 3) FROM DUAL; SELECT SUBSTR('Hello World!', 7) FROM DUAL; SELECT SUBSTR('Hello World!', 15) FROM DUAL; Exercise: Create an SQL command to list the data in the GRADES table with only the last 5 digits of student_id displayed. Instring Function INSTR() The INSTR() function in Oracle is used to identify the location of a string within another string. Here is its syntax: INSTR(sourceString, searchstring [, start [, nth occurrence]]) sourcestring the string to search searchstring the string value to search for in sourcestring start an optional point at which to start searching if other than character 1 nth occurrence optionally search for the nth occurrence of searchstring Return value: the location of searchstring within sourcestring (first character at which searchstring is found). 0 is returned if the string is not found. COSC 304 Lab Assignment 5 Page 2

3 Examples: INSTR('Hello World!', 'Wor') returns 7 INSTR('Hello World!', ' ') returns 6 INSTR('Hello World!', 'o') returns 5 INSTR('Hello World!', 'o', 6) returns 8 INSTR('Hello World!', 'l', 1, 2) returns 4 Try running each of the above examples using the system table DUAL: SELECT INSTR('Hello World!', 'Wor', 5) FROM DUAL; SELECT INSTR('Hello World!', ' ') FROM DUAL; SELECT INSTR('Hello World!', 'o') FROM DUAL; SELECT INSTR('Hello World!', 'o', 6) FROM DUAL; SELECT INSTR('Hello World!', 'l', 1, 2) FROM DUAL; SELECT INSTR('Hello World!', 'X') FROM DUAL; Concatenation Function CONCAT() The CONCAT() function in Oracle is used to create a new string that is the concatenation of two other strings. Here is its syntax: CONCAT(string1, string2) string1 the first (left) string to be concatenated string2 the second (right) string to be concatenated The datatype for each string can be any string datatype char, varchar2, nchar, clob, nvarchar Return value: a new string that is the concatenation of string1 with string2. Example: CONCAT('Hello', 'World!') returns HelloWorld Try running the above example using the system table DUAL: SELECT CONCAT('Hello', 'World!') FROM DUAL; Concatenation using As concatenation is a frequently used operation, an alternate, more concise technique is available using two pipe characters. You can concatenate two strings in a SELECT statement by putting two pipe characters (side by side, not separated by spaces) between the strings to be concatenated. Example: 'Hello' 'World!' returns HelloWorld Try running the above example using the system table DUAL: SELECT 'Hello' 'World!' FROM DUAL; COSC 304 Lab Assignment 5 Page 3

4 Special characters: You can include a single quote character inside a string by specifying two adjacent single quote characters for the single quote. This has the effect of escaping the quote character. You can include a newline character in a string by concatenating chr(10) to substrings of the string you want. Example: 'Hello' ' ''World!''' chr(10) 'See ya later.' returns Hello World See ya.later Try running the above example using the system table DUAL: SELECT 'Hello' ' ''World!''' chr(10) 'See ya later.' FROM DUAL; Testing For NULL Oracle provides the NVL() function that lets you replace a NULL value (returned as blank) with a string value. Here is the syntax for NVL(): NVL(expr1, expr2) expr1 any datatype expr2 any datatype If expr1 is character data, expr2 will be implicitly converted to the datatype of expr1 before comparison. If expr1 is numeric data, then Oracle will perform conversion on the argument with lower numeric precedence to the higher numeric precedence. Return value: expr2 is returned, if expr1 is NULL. Otherwise expr1 is returned. Example: To experiment with this function let s create a table with some NULL values: CREATE TABLE L5_students AS SELECT * FROM labdata.students WHERE ROWNUM <=5; INSERT INTO L5_students (student_id, stu_name ) values (' ', 'Sue Ng'); INSERT INTO L5_students (student_id, stu_name) values (' ', 'Jo Oaks'); Take a look at the data in the l5_students table: SELECT * FROM l5_students; You will notice that two of the seven rows have blanks (NULL values) for the program column. (Perhaps the students have yet to declare their program major). Let s run a more helpful SELECT statement using the NVL() function. COSC 304 Lab Assignment 5 Page 4

5 SELECT student_id, stu_name, NVL(program, 'Undeclared') Program FROM l5_students; Notice that those students who have declared their major have the correct value displayed for the program column, and those that have NULL values in the program column have the string Undeclared displayed for the column. Working With Dates In this section we will learn how to work with date data. It is important to remember that DATE is a data type in Oracle and all DATE values are always represented in Oracle using Oracle s own internal format which is of no interest to us. Furthermore, Oracle s internal DATE storage format has nothing to do with the way that a DATE value is displayed when you select a DATE column. Although you may want your DATE data formatted a certain way for display, you cannot store formatting with DATE values in a table. Formatting is something that you apply when displaying a DATE value, or when you want to express a DATE value using a certain format. Keep this in mind as you complete this section. A handy function that we can use to quickly get a DATE value for the current moment is sysdate. This function (expressed without parentheses) returns the DATE value of the current moment. We will use this function in our examples. There are two date-related datatypes in Oracle: DATE - stores the year, month, day, hour, minute, and seconds (after midnight). TIMESTAMP same as DATE with greater granularity. Microseconds are stored. We will not use or discuss this datatype further. To work with dates we need to use two functions: TO_CHAR() used to convert a DATE value into a formatted string (often for display purposes). TO_DATE() used to create a DATE value by specifying the date in a custom formatted string. TO_CHAR() Syntax: TO_CHAR( value, [ formatstring ], [ nls_language ] ) value a number or date value formatstring the string that specifies the format in which value is specified nls_language specifies the language in which month and day names and abbreviations are returned. It is not of interest for our purposes, so will be ignored. Return value: value converted to a string following the formatting specified in formatstring Examples: TO_CHAR( , '9999.9') would return '1210.7' TO_CHAR( , '9,999.99') would return '1,210.73' TO_CHAR( , '$9,999.00') would return '$1,210.73' TO_CHAR(21, '000099') would return '000021' TO_CHAR(sysdate, 'yyyy/mm/dd'); would return '2018/10/09' COSC 304 Lab Assignment 5 Page 5

6 TO_CHAR(sysdate, 'Month DD, YYYY'); would return 'October 09, 2018' TO_CHAR(sysdate, 'FMMonth DD, YYYY'); would return 'October 9, 2018' TO_CHAR(sysdate, 'MON DDth, YYYY'); would return 'Oct 09TH, 2018' TO_CHAR(sysdate, 'FMMON DDth, YYYY'); would return 'Oct 9TH, 2018' TO_CHAR(sysdate, 'FMMon ddth, YYYY'); would return 'Oct 9th, 2018' Note FM means to suppress the leading 0. TO_DATE() Syntax: TO_DATE(sourceString, [ formatstring ], [ nls_language ] ) sourcestring the string to be converted to a date. formatstring the string that specifies the format that the sourcestring is in. nls_language specifies the language in which month and day names and abbreviations are returned. It is not of interest for our purposes, so will be ignored. Return value: a DATE value that matches the date provided in sourcestring Example: TO_DATE('2018/07/09', 'yyyy/mm/dd') would return a date value of July 9, TO_DATE('070918', 'MMDDYY') would return a date value of July 9, TO_DATE(' ', 'yyyymmdd') would return a date value of Mar 15, All of the above returned dates would be for 0 seconds after midnight. The table below provides the different format specifiers that you can provide in a formatstring. YEAR YYYY Parameter YYY, YY, Y IYY, IY, I IYYY RRRR Year, spelled out 4-digit year Last 3, 2, or 1 digit(s) of year. Last 3, 2, or 1 digit(s) of ISO year. Explanation 4-digit year based on the ISO standard Accepts a 2-digit year and returns a 4-digit year. A value between 0-49 will return a 20xx year. A value between will return a 19xx year. Q Quarter of year (1, 2, 3, 4; JAN-MAR = 1). MM Month (01-12; JAN = 01). MON MONTH RM WW Abbreviated name of month. Name of month, padded with blanks to length of 9 characters. Roman numeral month (I-XII; JAN = I). Week of year (1-53) where week 1 starts on the first day of the year and continues to the seventh day of the year. COSC 304 Lab Assignment 5 Page 6

7 W IW D Day of week (1-7). DAY Week of month (1-5) where week 1 starts on the first day of the month and ends on the seventh. Week of year (1-52 or 1-53) based on the ISO standard. Name of day. DD Day of month (1-31). DDD Day of year (1-366). DY J Abbreviated name of day. HH Hour of day (1-12). HH12 Hour of day (1-12). HH24 Hour of day (0-23). MI Minute (0-59). SS Second (0-59). Julian day; the number of days since January 1, 4712 BC. SSSSS Seconds past midnight ( ). FF AM, A.M., PM, or P.M. Meridian indicator AD or A.D BC or B.C. Fractional seconds. Use a value from 1 to 9 after FF to indicate the number of digits in the fractional seconds. For example, 'FF4'. AD indicator BC indicator Try experimenting with the TO_CHAR() and TO_DATE() functions. You can create a test table and/or use the DUAL table. More Date Manipulation Oracle permits some arithmetic with dates. Specifically: You can add integers to dates. A single whole number, N has the value of one day. N/2 would have the value of half a day. N/24 would have the value of 1 hour. Examples: SYSDATE + 1 is a DATE corresponding to this time tomorrow. SYSDATE + 7 is a DATE corresponding to this day and time next week. SYSDATE + 6/24 is a DATE corresponding to 6 hours from now. SYSDATE + 1/4 is a DATE corresponding to 6 hours from now. SYSDATE + 5/24 is a DATE corresponding to 5 hours from now. SYSDATE + 10/(24*60*60) is a DATE corresponding to 10 seconds from now. You can take the difference between two DATEs also. The difference will let you know the difference between two DATEs. In other words, it will give the length of time in units of days between the two moments represented by the DATE values. COSC 304 Lab Assignment 5 Page 7

8 Example: To compare two dates you could do this (the most recent date would be returned): DECODE((dateA-dateB) abs(datea-dateb), 0, datea, dateb). An IF-Like Value Comparison Function DECODE() There is no If-Then function in Oracle, but you can accomplish the effect of an If-Then using the DECODE() function. Here is its syntax: DECODE(expression, searchvalue1, replacevalue1, searchvalue2, replacevalue2, searchvalue3, replacevalue3,..., default) expression the value to decode searchvaluen the Nth value to compare with expression replacevaluen the value to replace expression if searchvaluen matches expression Example: Consider the suppliers table in the LABDATA schema. In the example below, we want to list each supplier s name with the supplier s phone number. However, if you notice in the table, phone numbers for Kelowna suppliers do not include the 250 exchange value. So, let s use decode() to concatenate 250- to the beginning of phone numbers for Kelowna suppliers. SELECT Name, DECODE(city, 'Kelowna', '250-' phone, phone) Supplier_Phone FROM LABDATA.SUPPLIERS; Graded Exercises: 1. (3 marks) I would like to create Oracle user accounts for all students listed in the Students table (from labs two and three) that are similar to the username naming conventions that we do in COSC 304. Specifically, all usernames start with AS_ followed by the first initial of the student s first name, followed by the first three letters of the student s last name. However, we want a slightly more secure password than the ones we use. For a student s password, we will use their username concatenated with the last two digits of their student ID. Your job is to create a view called LAB5_1 that lists student names from the Students table followed by each student s username and password. Sort the results by student name. The first five lines of output should look like this: STUDENT_NAME USERNAME PASSWORD Ann Gibson AS_AGIB AS_AGIB02 Barry Clark AS_BCLA AS_BCLA02 Ben Crenshaw AS_BCRE AS_BCRE00 Darryl Sutter AS_DSUT AS_DSUT44 Dave Semenko AS_DSEM AS_DSEM55 Be sure to provide alias names for the columns of your view that exactly match the column names above. COSC 304 Lab Assignment 5 Page 8

9 The remaining exercises are related to the Dental database of Lab 4 These exercises will give you the opportunity to build advanced queries (using the Dental database that we used in Lab 4). When working on your queries, you may find it helpful to build them in steps. You must use joins in your queries as much as possible (rather than nested queries). 2. (4 marks) During each Wednesday in September and October, DK Dental Clinic is undergoing renovations to rooms L202, L203 and L204. Consequently, the appointments scheduled in those rooms during that month will need to be moved to different rooms. Your job is to list information (patient name, dentist first name, date, time and a note) for each Wednesday appointment in September and October (of 2018). Your query should list the information in the format shown below. Your query should list the appointment information along with a note that states Needs to move if the appointment is scheduled in one of the rooms being renovated. Order your results by date (and time) and save your query as a view with the name LAB5_2. The first 6 lines of your output should look like this: PATIENT DENTIST APPT_DATE APPT_TIME NOTES C. Gate Michael SEP 05, :30 PM S. Cane Newton SEP 12, :15 AM S. Cane Tulip SEP 12, :30 PM A. Fresh Phil SEP 19, :00 AM Needs to move A. Fresh Maureen SEP 19, :45 PM Needs to move A. Hammer Maurice OCT 03, :45 PM Be sure to provide alias names for the columns of your view that exactly match the column names above. 3. (6 marks) For each dentist in the L4_Dentists table, list the number of appointments that have been scheduled in rooms L202, L203 and L204 as shown in the output below. Order the results by dentist name. (Hint: consider summing values returned from the DECODE function, where you decode RoomNo). Save your query as view LAB5_3. Below shows the first eight lines of output for a correct solution. (Note: DO NOT put an aggregate function inside a DECODE function.) DENTIST_NAME L202 L203 L204 Total Isla de Groot Janice Sorghum Lara Nuerve Maureen Payne Maurice Larr Michael Avitee Newton Capp Orin Scrivello Be sure to provide alias names for the columns of your view that exactly match the column names above. COSC 304 Lab Assignment 5 Page 9

10 4. (6 marks) The Police are investigating crooked dentists who use their practice as a means of writing prescriptions for drugs after unnecessary procedures. Their investigators are auditing the number of surgeries and extractions performed be each dentist as these are the procedures where heavy painkillers are prescribed the most. They would like to list a count of the number of surgeries and extraction procedures performed by each dentist as well as the number of appointments. Write a query saved as a view named LAB5_4 that outputs a count for each dentist as shown below. You don t need to include dentists who didn t perform any of these procedures. DENTIST_NAME SURGERIES EXTRACTIONS TOTAL APPOINTMENTS Isla de Groot Janice Sorghum Maureen Payne Maurice Larr Michael Avitee Newton Capp Note: An Extraction procedure is one where the word Extraction appears in its description. Similarly, a Surgery procedure is one where the word Surgery appears in its description. Be sure to provide alias names for the columns of your view that exactly match the column names above. 5. (1 bonus mark). How much revenue has each dentist generated for the DK Dental Clinic? Write a query saved as a view named LAB5_5 that outputs each dentist s name followed by the revenue (total value of all procedures performed by the dentist (including future procedures)). The output should also include the total number of appointments and the average revenue per appointment. Here are the first few lines of output: DENTIST_NAME Revenue AVG_PER_APPT APPOINTMENTS Isla de Groot $9, $ Janice Sorghum $10, $1, Lara Nuerve $0.00 $ Maureen Payne $5, $ Maurice Larr $20, $ COSC 304 Lab Assignment 5 Page 10

Database Programming with SQL 5-1 Conversion Functions. Copyright 2015, Oracle and/or its affiliates. All rights reserved.

Database Programming with SQL 5-1 Objectives This lesson covers the following objectives: Provide an example of an explicit data-type conversion and an implicit data-type conversion Explain why it is important,