我有三个表：
integer -> integer.toString()前两个表联接查询代码
table req_specs(id int,testproject_id int,doc_id varchar)
table requirements(id int,srs_id int,req_doc_id varchar)
tables nodes_hierarchy(id int,name varchar,parent_id int,node_type_id int,node_order int)
public String getRequirementDocIDofProject(String testprojectName)
throws SQLException, InstantiationException, IllegalAccessException, ClassNotFoundException {
String req_doc_id = "";
initDB();
resultSet = statement.executeQuery("select * from req_specs " +
"INNER JOIN requirements reqs " +
"on req_specs.id =reqs.srs_id where req_specs.testproject_id=7165 ");
while (resultSet.next()) {
req_doc_id = req_doc_id+" "+resultSet.getString("req_doc_id");
}
close();
return req_doc_id;
}
返回正确的数据
后三个表联接查询代码
dbcon.getRequirementDocIDofProject("XXX"); public String getRequirementDocIDofProject(String testprojectName)
throws SQLException, InstantiationException, IllegalAccessException, ClassNotFoundException {
String req_doc_id = "";
initDB();
resultSet = statement.executeQuery("select * from req_specs INNER JOIN nodes_hierarchy nh " +
"on nh.id=req_specs.testproject_id " +
"INNER JOIN requirements reqs " +
"on req_specs.id =reqs.srs_id where nh.name='"+testprojectName+"' ");
while (resultSet.next()) {
req_doc_id = req_doc_id+" "+resultSet.getString("req_doc_id");
}
close();
return req_doc_id;
}
返回空。
但是当我将mysql放入navicat时，它会显示正确的值
dbcon.getRequirementDocIDofProject("XXX");答案 0 :(得分：-1)
我用代码找到了答案
"on req_specs.id =reqs.srs_id where nh.name='"+testprojectName+"' ");
字段nh.name的值不是英文字符。我将指定正确的字符编码。
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/dbname?useUnicode=yes&characterEncoding=UTF-8","username", "password");