[]ibatis and dollar sign Difference (#, $)

 How to use parameters in SQL statement table names in MyBatis

INSERT INTO Prefix_${table_name} (a, B, c) VALUES (#{a}, #{b}, #{c})

${} indicates direct use literal (literal value)

#{} indicates that this is a parameter

If table_name is "ABC"

Then ${table_name} is ABC

#{table_name} is "ABC"

Java code

2. 1. #可以进行预编译, type match, #变量名 # will be converted to the type of JDBC
4. $ does not perform data type matching, $ variable name $ directly replaces $name $ with the contents of name
6. For example:
8. SELECT * FROM tablename where id = #id #, assuming the value of ID is 12, where if the database field ID is a character type, then #id# represents ' 12 ', if the ID is integer, then #id# is
10. SELECT * FROM TableName where id= will be converted to JDBC? Put parameter is set to the value of ID
12. SELECT * FROM tablename WHERE id = $id $, if the field ID is integer, the SQL statement does not go wrong, but if the field ID is a character type,
14. Then the SQL statement should be written as a select * from table where id = ' $id $ '
18. 3. #方式能够很大程度防止sql注入.
20. The 4.$ method does not prevent SQL injection.
22. The 5.$ method is typically used to pass in database objects. For example, incoming table names.
24. 6. So ibatis use # better than $, generally can use the # do not use $.
26. In addition, use # #可以指定参数对应数据库的类型
28. Such as:
30. SELECT * FROM tablename WHERE id = #id: number#
34. Pay special attention when doing in,like operation
40. Summarize the following:
42. The $ number used in the specific Pojo class is also the non-basic type of the value, while the # number is used in the specific base type of the value
44. <sql id="Update_by_example_where_clause" >
46. <where>
48. <foreach collection="Example.oredcriteria" item="Criteria" separator="or" >
50. <if test="Criteria.valid" >
52. <trim prefix="(" Prefixoverrides="and" suffix=")" >
54. <foreach collection="Criteria.criteria" item="criterion" >
56. <choose>
58. <when test="Criterion.novalue" >
60. and ${criterion.condition}
62. </when>
64. <when test="Criterion.singlevalue" >
66. and ${criterion.condition} #{criterion.value}
68. </when>
70. <when test="Criterion.betweenvalue" >
72. and ${criterion.condition} #{criterion.value} and #{criterion.secondvalue}
74. </when>
76. <when test="Criterion.listvalue" >
78. and ${criterion.condition}
80. <foreach close=")" collection="Criterion.value" item="ListItem" open= "(" separator="," >
82. #{listitem}
84. </foreach>
86. </when>
88. </choose>
90. </foreach>
92. </trim>
94. </if>
96. </foreach>
98. </where>
100. </sql>

[]ibatis symbol differs from dollar sign (#, $)