Chapter 04-Using Conversion Functions and Conditional Expressions-General Functions
General Functions
The following functions work with any data ype and pertain to using nulls:
- NVL(expr1,expr2)
- NVL2(expr1,expr2,expr3)
- NULLIF(expr1,expr2)
- COALESCE(expr1,expr2,...,exprn)
NVL Function
Converts an null value to an actual value:
- Data types that can be used are date,character,and number.
- Data types must match:
- -NVL(commission_pct,0)
- -NVL(hire_date,'01-JAN-97')
- -NVL(job_id,'No Job Yet')
Demo-01:NVL(expr1,expr2)如果expr1为NULL，返回expr2；否则返回expr1
View Code
SQL> SELECT last_name,salary,NVL(commission_pct,0),(salary*12) + (salary*12*NVL(commission_pct,0)) AN_SAL FROM employees; LAST_NAME SALARY NVL(COMMISSION_PCT,0) AN_SAL ------------------------- ---------- --------------------- ---------- OConnell 2600 0 31200 Grant 2600 0 31200 Whalen 4400 0 52800 Hartstein 13000 0 156000 Fay 6000 0 72000 Mavris 6500 0 78000 Baer 10000 0 120000 Higgins 12008 0 144096 Gietz 8300 0 99600 King 24000 0 288000 Kochhar 17000 0 204000 LAST_NAME SALARY NVL(COMMISSION_PCT,0) AN_SAL ------------------------- ---------- --------------------- ---------- De Haan 17000 0 204000 Hunold 9000 0 108000 Ernst 6000 0 72000 Austin 4800 0 57600 Pataballa 4800 0 57600 Lorentz 4200 0 50400 Greenberg 12008 0 144096 Faviet 9000 0 108000 Chen 8200 0 98400 Sciarra 7700 0 92400 Urman 7800 0 93600 LAST_NAME SALARY NVL(COMMISSION_PCT,0) AN_SAL ------------------------- ---------- --------------------- ---------- Popp 6900 0 82800 Raphaely 11000 0 132000 Khoo 3100 0 37200 Baida 2900 0 34800 Tobias 2800 0 33600 Himuro 2600 0 31200 Colmenares 2500 0 30000 Weiss 8000 0 96000 Fripp 8200 0 98400 Kaufling 7900 0 94800 Vollman 6500 0 78000 LAST_NAME SALARY NVL(COMMISSION_PCT,0) AN_SAL ------------------------- ---------- --------------------- ---------- Mourgos 5800 0 69600 Nayer 3200 0 38400 Mikkilineni 2700 0 32400 Landry 2400 0 28800 Markle 2200 0 26400 Bissot 3300 0 39600 Atkinson 2800 0 33600 Marlow 2500 0 30000 Olson 2100 0 25200 Mallin 3300 0 39600 Rogers 2900 0 34800 LAST_NAME SALARY NVL(COMMISSION_PCT,0) AN_SAL ------------------------- ---------- --------------------- ---------- Gee 2400 0 28800 Philtanker 2200 0 26400 Ladwig 3600 0 43200 Stiles 3200 0 38400 Seo 2700 0 32400 Patel 2500 0 30000 Rajs 3500 0 42000 Davies 3100 0 37200 Matos 2600 0 31200 Vargas 2500 0 30000 Russell 14000 .4 235200 LAST_NAME SALARY NVL(COMMISSION_PCT,0) AN_SAL ------------------------- ---------- --------------------- ---------- Partners 13500 .3 210600 Errazuriz 12000 .3 187200 Cambrault 11000 .3 171600 Zlotkey 10500 .2 151200 Tucker 10000 .3 156000 Bernstein 9500 .25 142500 Hall 9000 .25 135000 Olsen 8000 .2 115200 Cambrault 7500 .2 108000 Tuvault 7000 .15 96600 King 10000 .35 162000 LAST_NAME SALARY NVL(COMMISSION_PCT,0) AN_SAL ------------------------- ---------- --------------------- ---------- Sully 9500 .35 153900 McEwen 9000 .35 145800 Smith 8000 .3 124800 Doran 7500 .3 117000 Sewall 7000 .25 105000 Vishney 10500 .25 157500 Greene 9500 .15 131100 Marvins 7200 .1 95040 Lee 6800 .1 89760 Ande 6400 .1 84480 Banda 6200 .1 81840 LAST_NAME SALARY NVL(COMMISSION_PCT,0) AN_SAL ------------------------- ---------- --------------------- ---------- Ozer 11500 .25 172500 Bloom 10000 .2 144000 Fox 9600 .2 138240 Smith 7400 .15 102120 Bates 7300 .15 100740 Kumar 6100 .1 80520 Abel 11000 .3 171600 Hutton 8800 .25 132000 Taylor 8600 .2 123840 Livingston 8400 .2 120960 Grant 7000 .15 96600 LAST_NAME SALARY NVL(COMMISSION_PCT,0) AN_SAL ------------------------- ---------- --------------------- ---------- Johnson 6200 .1 81840 Taylor 3200 0 38400 Fleaur 3100 0 37200 Sullivan 2500 0 30000 Geoni 2800 0 33600 Sarchand 4200 0 50400 Bull 4100 0 49200 Dellinger 3400 0 40800 Cabrio 3000 0 36000 Chung 3800 0 45600 Dilly 3600 0 43200 LAST_NAME SALARY NVL(COMMISSION_PCT,0) AN_SAL ------------------------- ---------- --------------------- ---------- Gates 2900 0 34800 Perkins 2500 0 30000 Bell 4000 0 48000 Everett 3900 0 46800 McCain 3200 0 38400 Jones 2800 0 33600 Walsh 3100 0 37200 Feeney 3000 0 36000 107 rows selected.
Demo-02:NVL2(expr1,expr2,expr3)如果expr1为NULL,返回expr3,否则返回expr2;
View Code
SQL> SELECT last_name,salary,commission_pct,NVL2(commission_pct,'SAL+COMM','SAL') incomme FROM employees WHERE department_id IN(50,80); LAST_NAME SALARY COMMISSION_PCT INCOMME ------------------------- ---------- -------------- -------- OConnell 2600 SAL Grant 2600 SAL Weiss 8000 SAL Fripp 8200 SAL Kaufling 7900 SAL Vollman 6500 SAL Mourgos 5800 SAL Nayer 3200 SAL Mikkilineni 2700 SAL Landry 2400 SAL Markle 2200 SAL LAST_NAME SALARY COMMISSION_PCT INCOMME ------------------------- ---------- -------------- -------- Bissot 3300 SAL Atkinson 2800 SAL Marlow 2500 SAL Olson 2100 SAL Mallin 3300 SAL Rogers 2900 SAL Gee 2400 SAL Philtanker 2200 SAL Ladwig 3600 SAL Stiles 3200 SAL Seo 2700 SAL LAST_NAME SALARY COMMISSION_PCT INCOMME ------------------------- ---------- -------------- -------- Patel 2500 SAL Rajs 3500 SAL Davies 3100 SAL Matos 2600 SAL Vargas 2500 SAL Taylor 3200 SAL Fleaur 3100 SAL Sullivan 2500 SAL Geoni 2800 SAL Sarchand 4200 SAL Bull 4100 SAL LAST_NAME SALARY COMMISSION_PCT INCOMME ------------------------- ---------- -------------- -------- Dellinger 3400 SAL Cabrio 3000 SAL Chung 3800 SAL Dilly 3600 SAL Gates 2900 SAL Perkins 2500 SAL Bell 4000 SAL Everett 3900 SAL McCain 3200 SAL Jones 2800 SAL Walsh 3100 SAL LAST_NAME SALARY COMMISSION_PCT INCOMME ------------------------- ---------- -------------- -------- Feeney 3000 SAL Russell 14000 .4 SAL+COMM Partners 13500 .3 SAL+COMM Errazuriz 12000 .3 SAL+COMM Cambrault 11000 .3 SAL+COMM Zlotkey 10500 .2 SAL+COMM Tucker 10000 .3 SAL+COMM Bernstein 9500 .25 SAL+COMM Hall 9000 .25 SAL+COMM Olsen 8000 .2 SAL+COMM Cambrault 7500 .2 SAL+COMM LAST_NAME SALARY COMMISSION_PCT INCOMME ------------------------- ---------- -------------- -------- Tuvault 7000 .15 SAL+COMM King 10000 .35 SAL+COMM Sully 9500 .35 SAL+COMM McEwen 9000 .35 SAL+COMM Smith 8000 .3 SAL+COMM Doran 7500 .3 SAL+COMM Sewall 7000 .25 SAL+COMM Vishney 10500 .25 SAL+COMM Greene 9500 .15 SAL+COMM Marvins 7200 .1 SAL+COMM Lee 6800 .1 SAL+COMM LAST_NAME SALARY COMMISSION_PCT INCOMME ------------------------- ---------- -------------- -------- Ande 6400 .1 SAL+COMM Banda 6200 .1 SAL+COMM Ozer 11500 .25 SAL+COMM Bloom 10000 .2 SAL+COMM Fox 9600 .2 SAL+COMM Smith 7400 .15 SAL+COMM Bates 7300 .15 SAL+COMM Kumar 6100 .1 SAL+COMM Abel 11000 .3 SAL+COMM Hutton 8800 .25 SAL+COMM Taylor 8600 .2 SAL+COMM LAST_NAME SALARY COMMISSION_PCT INCOMME ------------------------- ---------- -------------- -------- Livingston 8400 .2 SAL+COMM Johnson 6200 .1 SAL+COMM 79 rows selected.
Demo-03:NULLIF(expr1,expr2)如果expr1等于expr2，返回NULL；否则返回expr1
View Code
SQL> SELECT first_name,LENGTH(first_name) "expr1",last_name,LENGTH(last_name) "exp2",NULLIF(LENGTH(first_name),LENGTH(last_name)) result FROM employees; FIRST_NAME expr1 LAST_NAME exp2 RESULT -------------------- ---------- ------------------------- ---------- ---------- Ellen 5 Abel 4 5 Sundar 6 Ande 4 6 Mozhe 5 Atkinson 8 5 David 5 Austin 6 5 Hermann 7 Baer 4 7 Shelli 6 Baida 5 6 Amit 4 Banda 5 4 Elizabeth 9 Bates 5 9 Sarah 5 Bell 4 5 David 5 Bernstein 9 5 Laura 5 Bissot 6 5 FIRST_NAME expr1 LAST_NAME exp2 RESULT -------------------- ---------- ------------------------- ---------- ---------- Harrison 8 Bloom 5 8 Alexis 6 Bull 4 6 Anthony 7 Cabrio 6 7 Gerald 6 Cambrault 9 6 Nanette 7 Cambrault 9 7 John 4 Chen 4 Kelly 5 Chung 5 Karen 5 Colmenares 10 5 Curtis 6 Davies 6 Lex 3 De Haan 7 3 Julia 5 Dellinger 9 5 FIRST_NAME expr1 LAST_NAME exp2 RESULT -------------------- ---------- ------------------------- ---------- ---------- Jennifer 8 Dilly 5 8 Louise 6 Doran 5 6 Bruce 5 Ernst 5 Alberto 7 Errazuriz 9 7 Britney 7 Everett 7 Daniel 6 Faviet 6 arcerzhang 10 Fay 3 10 Kevin 5 Feeney 6 5 Jean 4 Fleaur 6 4 Tayler 6 Fox 3 6 Adam 4 Fripp 5 4 FIRST_NAME expr1 LAST_NAME exp2 RESULT -------------------- ---------- ------------------------- ---------- ---------- Timothy 7 Gates 5 7 Ki 2 Gee 3 2 Girard 6 Geoni 5 6 William 7 Gietz 5 7 Douglas 7 Grant 5 7 Kimberely 9 Grant 5 9 Nancy 5 Greenberg 9 5 Danielle 8 Greene 6 8 Peter 5 Hall 4 5 Michael 7 Hartstein 9 7 Shelley 7 Higgins 7 FIRST_NAME expr1 LAST_NAME exp2 RESULT -------------------- ---------- ------------------------- ---------- ---------- Guy 3 Himuro 6 3 Alexander 9 Hunold 6 9 Alyssa 6 Hutton 6 Charles 7 Johnson 7 Vance 5 Jones 5 Payam 5 Kaufling 8 5 Alexander 9 Khoo 4 9 Janette 7 King 4 7 Steven 6 King 4 6 Neena 5 Kochhar 7 5 Sundita 7 Kumar 5 7 FIRST_NAME expr1 LAST_NAME exp2 RESULT -------------------- ---------- ------------------------- ---------- ---------- Renske 6 Ladwig 6 James 5 Landry 6 5 David 5 Lee 3 5 Jack 4 Livingston 10 4 Diana 5 Lorentz 7 5 Jason 5 Mallin 6 5 Steven 6 Markle 6 James 5 Marlow 6 5 Mattea 6 Marvins 7 6 Randall 7 Matos 5 7 Susan 5 Mavris 6 5 FIRST_NAME expr1 LAST_NAME exp2 RESULT -------------------- ---------- ------------------------- ---------- ---------- Samuel 6 McCain 6 Allan 5 McEwen 6 5 Irene 5 Mikkilineni 11 5 Kevin 5 Mourgos 7 5 Julia 5 Nayer 5 Donald 6 OConnell 8 6 Christopher 11 Olsen 5 11 TJ 2 Olson 5 2 Lisa 4 Ozer 4 Karen 5 Partners 8 5 Valli 5 Pataballa 9 5 FIRST_NAME expr1 LAST_NAME exp2 RESULT -------------------- ---------- ------------------------- ---------- ---------- Joshua 6 Patel 5 6 Randall 7 Perkins 7 Hazel 5 Philtanker 10 5 Luis 4 Popp 4 Trenna 6 Rajs 4 6 Den 3 Raphaely 8 3 Michael 7 Rogers 6 7 John 4 Russell 7 4 Nandita 7 Sarchand 8 7 Ismael 6 Sciarra 7 6 John 4 Seo 3 4 FIRST_NAME expr1 LAST_NAME exp2 RESULT -------------------- ---------- ------------------------- ---------- ---------- Sarath 6 Sewall 6 Lindsey 7 Smith 5 7 William 7 Smith 5 7 Stephen 7 Stiles 6 7 Martha 6 Sullivan 8 6 Patrick 7 Sully 5 7 Jonathon 8 Taylor 6 8 Winston 7 Taylor 6 7 Sigal 5 Tobias 6 5 Peter 5 Tucker 6 5 Oliver 6 Tuvault 7 6 FIRST_NAME expr1 LAST_NAME exp2 RESULT -------------------- ---------- ------------------------- ---------- ---------- Jose Manuel 11 Urman 5 11 Peter 5 Vargas 6 5 Clara 5 Vishney 7 5 Shanta 6 Vollman 7 6 Alana 5 Walsh 5 Matthew 7 Weiss 5 7 Jennifer 8 Whalen 6 8 Eleni 5 Zlotkey 7 5 107 rows selected.
Using the COALESCE Function
- The advantage of the COALESCE function over the NVL function is that the COALESCE function can take multiple alternate values.
- If the first expression is not null,the COALESCE function returns that expression;otherwise,it does a COALESCE of the remaining expressions.
Demo-01:COALESCE(expr1,expr2,expr3...exprn)如果expr1,为NULL,接着判断expr2；如果expr2为NULL，接着判断expr3;直到返回第一个不为NULL值得exprn;
View Code
SQL> SELECT last_name,employee_id,COALESCE(TO_CHAR(commission_pct),TO_CHAR(manager_id),'No commission and no manager') FROM employees; LAST_NAME EMPLOYEE_ID COALESCE(TO_CHAR(COMMISSION_PCT),TO_CHAR ------------------------- ----------- ---------------------------------------- OConnell 198 124 Grant 199 124 Whalen 200 101 Hartstein 201 100 Fay 202 201 Mavris 203 101 Baer 204 101 Higgins 205 101 Gietz 206 205 King 100 No commission and no manager Kochhar 101 100 LAST_NAME EMPLOYEE_ID COALESCE(TO_CHAR(COMMISSION_PCT),TO_CHAR ------------------------- ----------- ---------------------------------------- De Haan 102 100 Hunold 103 102 Ernst 104 103 Austin 105 103 Pataballa 106 103 Lorentz 107 103 Greenberg 108 101 Faviet 109 108 Chen 110 108 Sciarra 111 108 Urman 112 108 LAST_NAME EMPLOYEE_ID COALESCE(TO_CHAR(COMMISSION_PCT),TO_CHAR ------------------------- ----------- ---------------------------------------- Popp 113 108 Raphaely 114 100 Khoo 115 114 Baida 116 114 Tobias 117 114 Himuro 118 114 Colmenares 119 114 Weiss 120 100 Fripp 121 100 Kaufling 122 100 Vollman 123 100 LAST_NAME EMPLOYEE_ID COALESCE(TO_CHAR(COMMISSION_PCT),TO_CHAR ------------------------- ----------- ---------------------------------------- Mourgos 124 100 Nayer 125 120 Mikkilineni 126 120 Landry 127 120 Markle 128 120 Bissot 129 121 Atkinson 130 121 Marlow 131 121 Olson 132 121 Mallin 133 122 Rogers 134 122 LAST_NAME EMPLOYEE_ID COALESCE(TO_CHAR(COMMISSION_PCT),TO_CHAR ------------------------- ----------- ---------------------------------------- Gee 135 122 Philtanker 136 122 Ladwig 137 123 Stiles 138 123 Seo 139 123 Patel 140 123 Rajs 141 124 Davies 142 124 Matos 143 124 Vargas 144 124 Russell 145 .4 LAST_NAME EMPLOYEE_ID COALESCE(TO_CHAR(COMMISSION_PCT),TO_CHAR ------------------------- ----------- ---------------------------------------- Partners 146 .3 Errazuriz 147 .3 Cambrault 148 .3 Zlotkey 149 .2 Tucker 150 .3 Bernstein 151 .25 Hall 152 .25 Olsen 153 .2 Cambrault 154 .2 Tuvault 155 .15 King 156 .35 LAST_NAME EMPLOYEE_ID COALESCE(TO_CHAR(COMMISSION_PCT),TO_CHAR ------------------------- ----------- ---------------------------------------- Sully 157 .35 McEwen 158 .35 Smith 159 .3 Doran 160 .3 Sewall 161 .25 Vishney 162 .25 Greene 163 .15 Marvins 164 .1 Lee 165 .1 Ande 166 .1 Banda 167 .1 LAST_NAME EMPLOYEE_ID COALESCE(TO_CHAR(COMMISSION_PCT),TO_CHAR ------------------------- ----------- ---------------------------------------- Ozer 168 .25 Bloom 169 .2 Fox 170 .2 Smith 171 .15 Bates 172 .15 Kumar 173 .1 Abel 174 .3 Hutton 175 .25 Taylor 176 .2 Livingston 177 .2 Grant 178 .15 LAST_NAME EMPLOYEE_ID COALESCE(TO_CHAR(COMMISSION_PCT),TO_CHAR ------------------------- ----------- ---------------------------------------- Johnson 179 .1 Taylor 180 120 Fleaur 181 120 Sullivan 182 120 Geoni 183 120 Sarchand 184 121 Bull 185 121 Dellinger 186 121 Cabrio 187 121 Chung 188 122 Dilly 189 122 LAST_NAME EMPLOYEE_ID COALESCE(TO_CHAR(COMMISSION_PCT),TO_CHAR ------------------------- ----------- ---------------------------------------- Gates 190 122 Perkins 191 122 Bell 192 123 Everett 193 123 McCain 194 123 Jones 195 123 Walsh 196 124 Feeney 197 124 107 rows selected.
