01. Configure JDBC Request
1. Add the required driver jar package
To use different databases, we need to introduce different jar packages.
Method 1: Copy the jar package directly to the lib directory of jmeter
mysql database:
Download mysql-connector-java-5.1.28.jar and put it in the lib directory of the jmeter root directory
sql server database:
Download sqljdbc4.jar and put it in the lib directory of the jmeter root directory
oracle database:
Put \product\10.2.0\db_1\jdbc\lib\ojdbc14.jar under the oracle data installation directory into the lib directory under the jmeter root directory
Method 2: Through Test Plan
If we don't use the method of copying the jar to the lib directory of jmeter, we can also use Jmeter's Test Plan to import the corresponding jar package, such as the jar package for importing oracle data below
2. Description of important parameters
Variable Name：
The name of the database connection pool, we can have multiple jdbc connection configurations, each of which can have a different name, and the appropriate connection pool can be selected for use in the jdbc request.
Database URL：
Database url, jdbc:mysql://host ip or machine name:mysql listening port number/database name, such as: jdbc:mysql://localhost:3306/test
JDBC Driver class：
JDBC driver
username：
Username for database login
password：
Password for database login
For the specific filling methods of different databases, you can refer to the following form: 
after filling, it is roughly as follows:
Important parameter description:
Variable Name：
The name of the database connection pool needs to be consistent with the name of the Variable Name Bound Pool of JDBC Connection Configuration
Query：
Do not add ";" at the end of the filled sql statement
Parameter pain：
parameter value
Parameter types：
Parameter type, please refer to: Javadoc for java.sql.Types
Variable names：
The name of the variable that saves the result returned by the sql statement
Result variable name：
Create an object variable to hold all returned results
Query timeout：
query timeout
Handle result set：
Define how to process the results returned by callable statements 
3. Execution results:
02. JDBC Request parameterization
method one)
Define variables and use variables in sql query:
1. Define a variable in Test Plan
(Of course, you can also use parameterization: Jmeter parameterization): 
2. Use ${variable name} in sql query to reference:
select * from test where name='${name}'
Method Two)
Use "?" as a placeholder in the sql query, and pass the parameter value and parameter type, as shown in the following figure:
1. The passed parameter value is a constant, as shown in the figure, two variables are passed, and multiple variables are separated by ", ". Here, if you have data of type int, you should also mark it as type varchar in Parameter types, otherwise it will not work. 
2. The passed parameter value is a variable, use ${variable name}
03. Variables names parameter
1. How to use:
The explanation given by the jmeter official website is: If a value is set for this parameter, it will save the data returned by the sql statement and the total number of rows of the returned data. Suppose, the sql statement returns 2 rows, 3 columns, and the variables names are set to A, C
Then the following variables would be set to:
A_#=2 (total number of lines)
A_1=column 1, row 1
A_2=column 1, row 2
C_#=2 (total number of rows)
C_1=column 3, row 1
C_2=column 3, row 2
If the return result is 0, then A_# and C_# will be set to 0, and other variables will not be set.
If 6 rows of data are returned for the first time, and only 3 rows of data are returned for the second time, then the 3 more rows of data variables for the first time will be cleared.
You can use KaTeX parse error: Expected group after '_' at position 3: {A_̲#}, {A_1}... to get the corresponding value
Example:
We still use the above database to find out all the data. The test table has 3 fields and 5 records (if you forget, you can go back to the first step to check)
1. Add a jdbc request called "parameter 4", add a "Debug Sampler" to view the output results, and set the variables name to column1, column2, column3: 2. Execution results 
:
Parse:
column1 represents all the data in the first column, and column1_# can get the number of rows in the first column
column1_n: Get the data of the nth row of the first column.
The functions of column2 and column3 are similar. If we only need the data of the first column and the third column, it can be written as column1, column3, and the "," in the middle cannot be omitted.
04. Result variable name parameter
1. How to use:
If you set a value for this parameter, it will create an object variable, save all the returned results, and get the specific value method:
columnValue = vars.getObject("resultObject").get(0).get("Column Name")
2. Execution result:
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