SQLite 将字符串拼接

SQLite中不是使用的‘+’来操作，是需要使用特殊符号“||”
例如：如果是其他字段形式的需要先装换为 字符型
使用CAST（字段名 as TEXT）

select CAST（column as TEXT） || '%'  from table 

用'||'拼接字符串

比如column是100的话 那结果就是100%

数字相加

SELECT 'A'+'B'  结果为0

SELECT "A"+"1"  结果为1

SELECT "A"+1   结果为1

SELECT 2+1  结果为3

=在“+”运算中，SQLite将字符串非数字串都当作0处理了

||  String Concatenation
*  Arithmetic Multiply
/  Arithmetic Divide
%  Arithmetic Modulus
+  Arithmetic Add
–  Arithmetic Subtract
<<  Bitwise Right shift
>>  Bitwise Left shift
&  Logical And
|  Logical Or
<  Relational Less than
<=  Relational Less than or equal to
>  Relational Greater than
>=  Relational Greater than or equal to
=  Relational Equal to
==  Relational Equal to
<>  Relational Not equal to
!=  Relational Not equal to
IN  Logical In
AND  Logical And
OR  Logical Or
LIKE  Relational String matching
GLOB  Relational Filename matching