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== CAST() also changes the result if you use it as part of a more complex expression such as CONCAT("Date: ",CAST(NOW() AS DATE)).==



<source lang="sql">
mysql>
mysql> SELECT CAST(1-2 AS UNSIGNED);</source>

== CAST(expr AS type), CONVERT(expr,type), CONVERT(expr USING transcoding_name)==

The CAST() and CONVERT() functions take a value of one type and produce a value of another type.
The type can be one of the following values:
<OL><LI>BINARY[(N)]</LI><LI>CHAR[(N)]</LI><LI>DATE</LI><LI>DATETIME</LI><LI>DECIMAL</LI><LI>SIGNED [INTEGER]</LI><LI>TIME</LI><LI>UNSIGNED [INTEGER]</LI></OL>
CONVERT() with USING is used to convert data between different character sets.
17. 3. CAST
17. 3. 1.
CAST(expr AS type), CONVERT(expr,type), CONVERT(expr USING transcoding_name)
17. 3. 2.
<A href="/Tutorial/MySQL/0340__Cast-Functions-Operators/Convertingthestringabcinthedefaultcharactersettothecorrespondingstringintheutf8characterset.htm">Converting the string "abc" in the default character set to the corresponding string in the utf8 character set:</a>
17. 3. 3.
<A href="/Tutorial/MySQL/0340__Cast-Functions-Operators/Convertblobcolumntochartype.htm">Convert blob column to char type</a>
17. 3. 4.
<A href="/Tutorial/MySQL/0340__Cast-Functions-Operators/ThecastfunctionsareusefulwhenyouwanttocreateacolumnwithaspecifictypeinaCREATESELECTstatement.htm">The cast functions are useful when you want to create a column with a specific type in a CREATE ... SELECT statement:</a>
17. 3. 5.
<A href="/Tutorial/MySQL/0340__Cast-Functions-Operators/CASTisusefulforsortingENUMcolumnsinlexicalorder.htm">CAST() is useful for sorting ENUM columns in lexical order.</a>
17. 3. 6.
<A href="/Tutorial/MySQL/0340__Cast-Functions-Operators/CASTalsochangestheresultifyouuseitaspartofamorecomplexexpressionsuchasCONCATDateCASTNOWASDATE.htm">CAST() also changes the result if you use it as part of a more complex expression such as CONCAT("Date: ",CAST(NOW() AS DATE)).</a>
17. 3. 7.
<A href="/Tutorial/MySQL/0340__Cast-Functions-Operators/SELECTCAST1ASUNSIGNED20.htm">SELECT CAST(1 AS UNSIGNED) - 2.0;</a>

== CAST() is useful 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:



<source lang="sql">
mysql>
mysql> SELECT enum_col FROM tbl_name ORDER BY CAST(enum_col AS CHAR);
mysql>
mysql></source>

== Convert blob column to char type==



<source lang="sql">
mysql>
mysql> SELECT "A" LIKE CONVERT(blob_col USING latin1) FROM tbl_name;
mysql>
mysql></source>

== Converting the string "abc" in the default character set to the corresponding string in the utf8 character set:==



<source lang="sql">
mysql>
mysql> SELECT CONVERT("abc" USING utf8);
+---------------------------+
| CONVERT("abc" USING utf8) |
+---------------------------+
| abc |
+---------------------------+
1 row in set (0.00 sec)
mysql></source>

== SELECT CAST(1 AS UNSIGNED) - 2.0;==



<source lang="sql">
mysql>
mysql> SELECT CAST(1 AS UNSIGNED) - 2.0;
+---------------------------+
| CAST(1 AS UNSIGNED) - 2.0 |
+---------------------------+
| -1.0 |
+---------------------------+
1 row in set (0.00 sec)
mysql></source>

== The cast functions are useful when you want to create a column with a specific type in a CREATE ... SELECT statement:==



<source lang="sql">
mysql>
mysql> CREATE TABLE new_table SELECT CAST("2000-01-01" AS DATE);
Query OK, 1 row affected (0.08 sec)
Records: 1 Duplicates: 0 Warnings: 0
mysql>
mysql> select * from new_table;
+----------------------------+
| CAST("2000-01-01" AS DATE) |
+----------------------------+
| 2000-01-01 |
+----------------------------+
1 row in set (0.00 sec)
mysql>
mysql> drop table new_table;
Query OK, 0 rows affected (0.00 sec)</source>

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