MySQL Cast functions and Operators

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MySQL Cast functions and Operators

MySQL BINARY Operator

The BINARY operator is used to force a column comparison byte by byte rather than character by character and comparison becomes case sensitive. BINARY also causes trailing spaces to be significant.

Example :

mysql> SELECT 'x' = 'X';

+-----------+

| 'x' = 'X' |

+-----------+

|         1 |

+-----------+

1 row in set (0.00 sec)

 

mysql> SELECT BINARY 'x' = 'X';

+------------------+

| BINARY 'x' = 'X' |

+------------------+

|                0 |

+------------------+

1 row in set (0.05 sec)

mysql> SELECT 'x' = ' X';

+------------+

| 'x' = ' X' |

+------------+

|          0 |

+------------+

1 row in set (0.00 sec)

 

mysql> SELECT BINARY 'x' = ' X';

+-------------------+

| BINARY 'x' = ' X' |

+-------------------+

|                 0 |

+-------------------+

1 row in set (0.00 sec)

MySQL CAST() function

The CAST() function is used to convert the type of an expression to a specified type. The function is similar to CONVERT() function.

Syntax :

CAST() function :

CAST(expr AS type))

           

CONVERT() function :

CONVERT(expr USING transcoding_name)

List of target types :

  • BINARY[(N)] : BINARY produces a string with the BINARY data type. If the optional length N is given, BINARY(N) causes the cast to use no more than N bytes of the argument.
  • CHAR[(N)] : For CHAR(N), CAST() function can not use any more than N characters of the argument.
  • DATE
  • DATETIME
  • DECIMAL[(M[,D])]
  • SIGNED [INTEGER]
  • TIME
  • UNSIGNED [INTEGER]

Example : DECIMAL type

The following code converts DECIMAL values (commision_pct, 2,2) into CHAR values and displayes the first name and commission information (where commision_pct>.30) from employees table.

Sample table : employees

EMPLOYEE_ID FIRST_NAME LAST_NAME EMAIL PHONE_NUMBER HIRE_DATE JOB_ID SALARY COMMISSION_PCT MANAGER_ID DEPARTMENT_ID
100 Steven King SKING 515.123.4567 17-Jun-87 AD_PRES 24000     90
101 Neena Kochhar NKOCHHAR 515.123.4568 21-Sep-89 AD_VP 17000   100 90
102 Lex De Haan LDEHAAN 515.123.4569 13-Jan-93 AD_VP 17000   100 90
103 Alexander Hunold AHUNOLD 590.423.4567 3-Jan-90 IT_PROG 9000   102 60
104 Bruce Ernst BERNST 590.423.4568 21-May-91 IT_PROG 6000   103 60
105 David Austin DAUSTIN 590.423.4569 25-Jun-97 IT_PROG 4800   103 60
106 Valli Pataballa VPATABAL 590.423.4560 5-Feb-98 IT_PROG 4800   103 60
107 Diana Lorentz DLORENTZ 590.423.5567 7-Feb-99 IT_PROG 4200   103 60
108 Nancy Greenberg NGREENBE 515.124.4569 17-Aug-94 FI_MGR 12000   101 100
109 Daniel Faviet DFAVIET 515.124.4169 16-Aug-94 FI_ACCOUNT 9000   108 100
110 John Chen JCHEN 515.124.4269 28-Sep-97 FI_ACCOUNT 8200   108 100
111 Ismael Sciarra ISCIARRA 515.124.4369 30-Sep-97 FI_ACCOUNT 7700   108 100
112 Jose Manuel Urman JMURMAN 515.124.4469 7-Mar-98 FI_ACCOUNT 7800   108 100
113 Luis Popp LPOPP 515.124.4567 7-Dec-99 FI_ACCOUNT 6900   108 100
114 Den Raphaely DRAPHEAL 515.127.4561 7-Dec-94 PU_MAN 11000   100 30
115 Alexander Khoo AKHOO 515.127.4562 18-May-95 PU_CLERK 3100   114 30
116 Shelli Baida SBAIDA 515.127.4563 24-Dec-97 PU_CLERK 2900   114 30
117 Sigal Tobias STOBIAS 515.127.4564 24-Jul-97 PU_CLERK 2800   114 30
118 Guy Himuro GHIMURO 515.127.4565 15-Nov-98 PU_CLERK 2600   114 30
119 Karen Colmenares KCOLMENA 515.127.4566 10-Aug-99 PU_CLERK 2500   114 30
120 Matthew Weiss MWEISS 650.123.1234 18-Jul-96 ST_MAN 8000   100 50
121 Adam Fripp AFRIPP 650.123.2234 10-Apr-97 ST_MAN 8200   100 50
122 Payam Kaufling PKAUFLIN 650.123.3234 1-May-95 ST_MAN 7900   100 50
123 Shanta Vollman SVOLLMAN 650.123.4234 10-Oct-97 ST_MAN 6500   100 50
124 Kevin Mourgos KMOURGOS 650.123.5234 16-Nov-99 ST_MAN 5800   100 50
125 Julia Nayer JNAYER 650.124.1214 16-Jul-97 ST_CLERK 3200   120 50
126 Irene Mikkilineni IMIKKILI 650.124.1224 28-Sep-98 ST_CLERK 2700   120 50
127 James Landry JLANDRY 650.124.1334 14-Jan-99 ST_CLERK 2400   120 50
128 Steven Markle SMARKLE 650.124.1434 8-Mar-00 ST_CLERK 2200   120 50
129 Laura Bissot LBISSOT 650.124.5234 20-Aug-97 ST_CLERK 3300   121 50
130 Mozhe Atkinson MATKINSO 650.124.6234 30-Oct-97 ST_CLERK 2800   121 50
131 James Marlow JAMRLOW 650.124.7234 16-Feb-97 ST_CLERK 2500   121 50
132 TJ Olson TJOLSON 650.124.8234 10-Apr-99 ST_CLERK 2100   121 50
133 Jason Mallin JMALLIN 650.127.1934 14-Jun-96 ST_CLERK 3300   122 50
134 Michael Rogers MROGERS 650.127.1834 26-Aug-98 ST_CLERK 2900   122 50
135 Ki Gee KGEE 650.127.1734 12-Dec-99 ST_CLERK 2400   122 50
136 Hazel Philtanker HPHILTAN 650.127.1634 6-Feb-00 ST_CLERK 2200   122 50
137 Renske Ladwig RLADWIG 650.121.1234 14-Jul-95 ST_CLERK 3600   123 50
138 Stephen Stiles SSTILES 650.121.2034 26-Oct-97 ST_CLERK 3200   123 50
139 John Seo JSEO 650.121.2019 12-Feb-98 ST_CLERK 2700   123 50
140 Joshua Patel JPATEL 650.121.1834 6-Apr-98 ST_CLERK 2500   123 50
141 Trenna Rajs TRAJS 650.121.8009 17-Oct-95 ST_CLERK 3500   124 50
142 Curtis Davies CDAVIES 650.121.2994 29-Jan-97 ST_CLERK 3100   124 50
143 Randall Matos RMATOS 650.121.2874 15-Mar-98 ST_CLERK 2600   124 50
144 Peter Vargas PVARGAS 650.121.2004 9-Jul-98 ST_CLERK 2500   124 50
145 John Russell JRUSSEL 011.44.1344.429268 1-Oct-96 SA_MAN 14000 0.4 100 80
146 Karen Partners KPARTNER 011.44.1344.467268 5-Jan-97 SA_MAN 13500 0.3 100 80
147 Alberto Errazuriz AERRAZUR 011.44.1344.429278 10-Mar-97 SA_MAN 12000 0.3 100 80
148 Gerald Cambrault GCAMBRAU 011.44.1344.619268 15-Oct-99 SA_MAN 11000 0.3 100 80
149 Eleni Zlotkey EZLOTKEY 011.44.1344.429018 29-Jan-00 SA_MAN 10500 0.2 100 80
150 Peter Tucker PTUCKER 011.44.1344.129268 30-Jan-97 SA_REP 10000 0.3 145 80
151 David Bernstein DBERNSTE 011.44.1344.345268 24-Mar-97 SA_REP 9500 0.25 145 80
152 Peter Hall PHALL 011.44.1344.478968 20-Aug-97 SA_REP 9000 0.25 145 80
153 Christopher Olsen COLSEN 011.44.1344.498718 30-Mar-98 SA_REP 8000 0.2 145 80
154 Nanette Cambrault NCAMBRAU 011.44.1344.987668 9-Dec-98 SA_REP 7500 0.2 145 80
155 Oliver Tuvault OTUVAULT 011.44.1344.486508 23-Nov-99 SA_REP 7000 0.15 145 80
156 Janette King JKING 011.44.1345.429268 30-Jan-96 SA_REP 10000 0.35 146 80
157 Patrick Sully PSULLY 011.44.1345.929268 4-Mar-96 SA_REP 9500 0.35 146 80
158 Allan McEwen AMCEWEN 011.44.1345.829268 1-Aug-96 SA_REP 9000 0.35 146 80
159 Lindsey Smith LSMITH 011.44.1345.729268 10-Mar-97 SA_REP 8000 0.3 146 80
160 Louise Doran LDORAN 011.44.1345.629268 15-Dec-97 SA_REP 7500 0.3 146 80
161 Sarath Sewall SSEWALL 011.44.1345.529268 3-Nov-98 SA_REP 7000 0.25 146 80
162 Clara Vishney CVISHNEY 011.44.1346.129268 11-Nov-97 SA_REP 10500 0.25 147 80
163 Danielle Greene DGREENE 011.44.1346.229268 19-Mar-99 SA_REP 9500 0.15 147 80
164 Mattea Marvins MMARVINS 011.44.1346.329268 24-Jan-00 SA_REP 7200 0.1 147 80
165 David Lee DLEE 011.44.1346.529268 23-Feb-00 SA_REP 6800 0.1 147 80
166 Sundar Ande SANDE 011.44.1346.629268 24-Mar-00 SA_REP 6400 0.1 147 80
167 Amit Banda ABANDA 011.44.1346.729268 21-Apr-00 SA_REP 6200 0.1 147 80
168 Lisa Ozer LOZER 011.44.1343.929268 11-Mar-97 SA_REP 11500 0.25 148 80
169 Harrison Bloom HBLOOM 011.44.1343.829268 23-Mar-98 SA_REP 10000 0.2 148 80
170 Tayler Fox TFOX 011.44.1343.729268 24-Jan-98 SA_REP 9600 0.2 148 80
171 William Smith WSMITH 011.44.1343.629268 23-Feb-99 SA_REP 7400 0.15 148 80
172 Elizabeth Bates EBATES 011.44.1343.529268 24-Mar-99 SA_REP 7300 0.15 148 80
173 Sundita Kumar SKUMAR 011.44.1343.329268 21-Apr-00 SA_REP 6100 0.1 148 80
174 Ellen Abel EABEL 011.44.1644.429267 11-May-96 SA_REP 11000 0.3 149 80
175 Alyssa Hutton AHUTTON 011.44.1644.429266 19-Mar-97 SA_REP 8800 0.25 149 80
176 Jonathon Taylor JTAYLOR 011.44.1644.429265 24-Mar-98 SA_REP 8600 0.2 149 80
177 Jack Livingston JLIVINGS 011.44.1644.429264 23-Apr-98 SA_REP 8400 0.2 149 80
178 Kimberely Grant KGRANT 011.44.1644.429263 24-May-99 SA_REP 7000 0.15 149  
179 Charles Johnson CJOHNSON 011.44.1644.429262 4-Jan-00 SA_REP 6200 0.1 149 80
180 Winston Taylor WTAYLOR 650.507.9876 24-Jan-98 SH_CLERK 3200   120 50
181 Jean Fleaur JFLEAUR 650.507.9877 23-Feb-98 SH_CLERK 3100   120 50
182 Martha Sullivan MSULLIVA 650.507.9878 21-Jun-99 SH_CLERK 2500   120 50
183 Girard Geoni GGEONI 650.507.9879 3-Feb-00 SH_CLERK 2800   120 50
184 Nandita Sarchand NSARCHAN 650.509.1876 27-Jan-96 SH_CLERK 4200   121 50
185 Alexis Bull ABULL 650.509.2876 20-Feb-97 SH_CLERK 4100   121 50
186 Julia Dellinger JDELLING 650.509.3876 24-Jun-98 SH_CLERK 3400   121 50
187 Anthony Cabrio ACABRIO 650.509.4876 7-Feb-99 SH_CLERK 3000   121 50
188 Kelly Chung KCHUNG 650.505.1876 14-Jun-97 SH_CLERK 3800   122 50
189 Jennifer Dilly JDILLY 650.505.2876 13-Aug-97 SH_CLERK 3600   122 50
190 Timothy Gates TGATES 650.505.3876 11-Jul-98 SH_CLERK 2900   122 50
191 Randall Perkins RPERKINS 650.505.4876 19-Dec-99 SH_CLERK 2500   122 50
192 Sarah Bell SBELL 650.501.1876 4-Feb-96 SH_CLERK 4000   123 50
193 Britney Everett BEVERETT 650.501.2876 3-Mar-97 SH_CLERK 3900   123 50
194 Samuel McCain SMCCAIN 650.501.3876 1-Jul-98 SH_CLERK 3200   123 50
195 Vance Jones VJONES 650.501.4876 17-Mar-99 SH_CLERK 2800   123 50
196 Alana Walsh AWALSH 650.507.9811 24-Apr-98 SH_CLERK 3100   124 50
197 Kevin Feeney KFEENEY 650.507.9822 23-May-98 SH_CLERK 3000   124 50
198 Donald OConnell DOCONNEL 650.507.9833 21-Jun-99 SH_CLERK 2600   124 50
199 Douglas Grant DGRANT 650.507.9844 13-Jan-00 SH_CLERK 2600   124 50
200 Jennifer Whalen JWHALEN 515.123.4444 17-Sep-87 AD_ASST 4400   101 10
201 Michael Hartstein MHARTSTE 515.123.5555 17-Feb-96 MK_MAN 13000   100 20
202 Pat Fay PFAY 603.123.6666 17-Aug-97 MK_REP 6000   201 20
203 Susan Mavris SMAVRIS 515.123.7777 7-Jun-94 HR_REP 6500   101 40
204 Hermann Baer HBAER 515.123.8888 7-Jun-94 PR_REP 10000   101 70
205 Shelley Higgins SHIGGINS 515.123.8080 7-Jun-94 AC_MGR 12000   101 110
206 William Gietz WGIETZ 515.123.8181 7-Jun-94 AC_ACCOUNT 8300   205 110

mysql> SELECT first_name, CONCAT('Commisison Pct. - ',CAST(commission_pct AS CHAR)) from employees WHERE commission_pct>.30;

+------------+-----------------------------------------------------------+

| first_name | CONCAT('Commisison Pct. - ',CAST(commission_pct AS CHAR)) |

+------------+-----------------------------------------------------------+

| John       | Commisison Pct. - 0.40                                    |

| Janette    | Commisison Pct. - 0.35                                    |

| Patrick    | Commisison Pct. - 0.35                                    |

| Allan      | Commisison Pct. - 0.35                                    |

+------------+-----------------------------------------------------------+

4 rows in set (0.00 sec)

Example : DATETIME type

The following SQL statement converts DATE values (hire-date) into DATETIME values and display the first name and joining date-time information from employees table.

mysql> SELECT first_name, CAST(hire_date AS DATETIME) 'Joining  Date' from employees where hire_date>('1987-09-15') ;

+------------+---------------------+

| first_name | Joining  Date       |

+------------+---------------------+

| Randall    | 1987-09-16 00:00:00 |

| Sarah      | 1987-09-17 00:00:00 |

| Britney    | 1987-09-18 00:00:00 |

| Samuel     | 1987-09-19 00:00:00 |

| Vance      | 1987-09-20 00:00:00 |

| Alana      | 1987-09-21 00:00:00 |

| Kevin      | 1987-09-22 00:00:00 |

| Donald     | 1987-09-23 00:00:00 |

| Douglas    | 1987-09-24 00:00:00 |

| Jennifer   | 1987-09-25 00:00:00 |

| Michael    | 1987-09-26 00:00:00 |

| Pat        | 1987-09-27 00:00:00 |

| Susan      | 1987-09-28 00:00:00 |

| Hermann    | 1987-09-29 00:00:00 |

| Shelley    | 1987-09-30 00:00:00 |

| William    | 1987-10-01 00:00:00 |

+------------+---------------------+

16 rows in set (0.04 sec)

CAST() and CONVERT(... USING ...) are standard SQL syntax. The non-USING form of CONVERT() is ODBC syntax. CONVERT() function with USING clause is used to convert data between different character sets. In the following example the MySQL statement converts the string 'bird', the default character set to the corresponding string in the utf8 character set :

mysql> SELECT CONVERT('bird' USING utf8);

+----------------------------+

| CONVERT('bird' USING utf8) |

+----------------------------+

| bird                       |

+----------------------------+

1 row in set (0.00 sec)

The cast functions are useful in the following situation :
- when you want to create a column with a specific type in a CREATE TABLE ... SELECT statement :

mysql> CREATE TABLE table2 SELECT CAST('2012-12-12' AS DATE);

Query OK, 1 row affected (1.40 sec)

Records: 1  Duplicates: 0  Warnings: 0

 

mysql> SELECT * FROM TABLE2;

+----------------------------+

| CAST('2012-12-12' AS DATE) |

+----------------------------+

| 2012-12-12                 |

+----------------------------+

1 row in set (0.04 sec)

- for sorting ENUM columns in lexical order. Normally, sorting of ENUM columns occurs using the internal numeric values. Casting the values to CHAR results in a lexical sort:

SELECT enum_col FROM table_name ORDER BY CAST(enum_col AS CHAR);

MySQL supports arithmetic with both signed and unsigned 64-bit values. When using numeric operators (such as + or -) and if one of the operands is an unsigned integer, the result will be unsigned by default.

mysql> SELECT CAST(CAST(1-2 AS UNSIGNED) AS SIGNED);

+---------------------------------------+

| CAST(CAST(1-2 AS UNSIGNED) AS SIGNED) |

+---------------------------------------+

|                                    -1 |

+---------------------------------------+

1 row in set (0.00 sec)

 

mysql> SELECT CAST(1-2 AS UNSIGNED);

+-----------------------+

| CAST(1-2 AS UNSIGNED) |

+-----------------------+

|  18446744073709551615 |

+-----------------------+

1 row in set (0.00 sec)

If any operand is a floating-point value, the result will be a floating-point value.

mysql> SELECT CAST(11 AS UNSIGNED) - 3.0;
+----------------------------+
| CAST(11 AS UNSIGNED) - 3.0 |
+----------------------------+
|                        8.0 |
+----------------------------+
1 row in set (0.00 sec)