The query code and query:
ps = conn.prepareStatement("select instance_id, ? from eam_measurement where resource_id in (select RESOURCE_ID from eam_res_grp_res_map where resource_group_id = ?) and DSN like '?' order by 2");
ps.setString(1,"SUBSTR(DSN,27,16)");
ps.setInt(2,defaultWasGroup);
ps.setString(3,"%Module=jvmRuntimeModule:freeMemory%");
rs = ps.executeQuery();
while (rs.next()) { bla blah blah blah ...
Returns an empty ResultSet.
Through basic debugging I have found its the third bind that is the problem i.e.
DSN like '?'
I have tried all kinds of variations, the most sensible of which seemed to be using:
DSN like concat('%',?,'%')
but that does not work as I am missing the ' on either side of the concatenated string so I try:
DSN like ' concat('%',Module=P_STAG_JDBC01:poolSize,'%') ' order by 2
but I just cannot seem to find a way to get them in that works.
What am I missing?
First, the PreparedStatement placeholders (those ? things) are for column values only, not for table names, column names, SQL functions/clauses, etcetera. Better use String#format() instead. Second, you should not quote the placeholders like '?', it would only malform the final query. The PreparedStatement setters already do the quoting (and escaping) job for you.
Here's the fixed SQL:
private static final String SQL = "select instance_id, %s from eam_measurement"
+ " where resource_id in (select RESOURCE_ID from eam_res_grp_res_map where"
+ " resource_group_id = ?) and DSN like ? order by 2");
Here is how to use it:
String sql = String.format(SQL, "SUBSTR(DSN,27,16)"); // This replaces the %s.
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setInt(1, defaultWasGroup);
preparedStatement.setString(2, "%Module=jvmRuntimeModule:freeMemory%");
See also:
Sun JDBC tutorial: Using Prepared Statements
Format string syntax
If you want to use LIKE in prepared statement and also want to use % characters in LIKE;
write prepared statement as normally " .... LIKE ? ...." and while assigning parameter value to question mark use
ps.setString(1, "%" + "your string value" + "%");
This will work :)
There are two problems with your statement. You have to understand how bind variables work. The query is not processed by substituing the characters ? with your parameters. Instead, the statement is compiled with placeholders and then, during execution, the actual values of the parameters are given to the DB.
In other words, you parse the following query:
SELECT instance_id, :p1
FROM eam_measurement
WHERE resource_id IN (SELECT RESOURCE_ID
FROM eam_res_grp_res_map
WHERE resource_group_id = :p2)
AND DSN LIKE '?'
ORDER BY 2
I'm pretty sure the last parameter will be ignored because it is in a delimited character string. Even if it is not ignored, it does not make sense to have ' characters around because Oracle won't bind a parameter in a string (I'm surprised it hasn't raised any error, do you catch exceptions ?).
Now if you replace your DNS LIKE '?' with DSN LIKE ? and bind "%Module=jvmRuntimeModule:freeMemory%" this will make sense and should return the correct rows.
You still have the problem with your first parameter, it won't do what you expect, i-e the query that will be executed will be equivalent to the following query:
SELECT instance_id, 'SUBSTR(DSN,27,16)'
FROM ...
which is not at all the same as
SELECT instance_id, SUBSTR(DSN,27,16)
FROM ...
I would suggest parsing (=prepareStatement) the following query if you expect the SUBSTR to be dynamic:
SELECT instance_id, SUBSTR(DSN,?,?)
FROM eam_measurement
WHERE resource_id IN (SELECT RESOURCE_ID
FROM eam_res_grp_res_map
WHERE resource_group_id = ?)
AND DSN LIKE ?
ORDER BY 2
Omit the ' around the ?. Without the ', ? is a placeholder for a parameter. With it, it's an SQL string (i.e. the same as "?" in Java).
Then you must concatenate the string on the Java side; you can't pass SQL functions as parameters to queries; only basic values (like string, integer, etc) because the JDBC driver will convert the parameter to the SQL type the database expects and it cannot execute SQL functions in this step.
You can try:
String beforeAndAfter = "%" + yourVariable + "%";
PreparedStatement ps = con.prepareStatement(
"select columname from tablename where LOWER(columnname) LIKE LOWER('"+var+"%')");
Here var is the variable in which value that is to be searched is stored...
This should work:
"\'" + "?" + "\'"
Related
query="select * from books where BookName LIKE \"%" +txt1.getText()+"%\"";
this is for mysql server database code.
what will be change for oracle?
DO NOT build SQL queries using string concatenation - you should be using bind parameters.
Your query string should be:
query="select * from books where BookName LIKE ?";
and then you can do something like:
Class.forName( "oracle.jdbc.OracleDriver" ); // If you are using the Oracle driver.
Connection con = DriverManager.getConnection(
"jdbc:oracle:thin:#localhost:1521:XE",
"username",
"password"
);
final String query="select * from books where BookName LIKE ?";
PreparedStatement ps = conn.prepareStatement(query);
ps.setString( 1, "%" + txt1.getText() + "%" );
ResultSet rs = ps.executeQuery();
// Loop through the result set.
// Close statement/connections
(you will need to handle exceptions, etc.)
and:
You should not need to change the query to swap between MySQL and Oracle (just change the driver and connection string).
You do not need to escape any single or double quotation marks in the input string.
You are protected from SQL injection attacks.
Oracle can cache the query with the bind parameter and does not have to re-parse / re-compile it when the bind parameter changes.
If you are going to write the query as a string then string literals are surrounded by single quotes (not double quotes) in SQL:
query="select * from books where BookName LIKE '%your_string%'";
and you need to make sure that any single quotes in your string are properly escaped (but just use a bind parameter instead).
problem solved with this..
query="select * from books where BookName LIKE '%" +txt1.getText()+"%'";
thanks everyone :)
My query
attributes.replace(" ' ", "");
//also used SET "+attributes+"
String sql;
sql = "UPDATE diseaseinfo"
+ " SET ?=?"
+ "WHERE companyname = 'mycom' && diseaseName =?";
PreparedStatement preparedStmt = connects.prepareStatement(sql);
preparedStmt.setString(1, attributes);
preparedStmt.setString(2, attrData);
preparedStmt.setString(3, medname);
System.out.println(preparedStmt);
it is giving me an error because query set the column name in string so it become like this on causes
UPDATE diseaseinfo SET 'causes'='abc' WHERE companyname = 'mycom' and diseaseName ='fever'
and through this question I get to know that I can't add dynamic column by prepared statement: https://stackoverflow.com/a/3136049/7794329
Now, the real question comes up: suppose if I will use a simple update query like in this question: jdbc dymanic sql query with variable containg 's
It says you can't enter value with 's in your simple sql query because it will again make the query syntactical error for example :
SELECT * FROM diseaseinfo WHERE diseaseName = 'Adult Still's disease' AND name = 'add';
Here it wont execute because of ' 's on 'Adult Still's
Then it won't work with simple query. What should I do now? What to use? To set dynamic column with taking care of 's in the query.
I am not worried about SQL injection because i am working on local. And I just want my query to be executed.
Right. We can't supply identifiers as bind parameters. The name of the column has to be part of the SQL text.
We can dynamically incorporate the name of the column into the SQL text with something like this:
sql = "UPDATE diseaseinfo"
+ " SET `" + colname + "` = ?"
+ " WHERE companyname = 'mycom' AND diseaseName = ?";
And supply values for the two remaining bind parameters
preparedStmt.setString(1, attrData);
preparedStmt.setString(2, medname);
And you are absolutely correct about being concerned about SQL Injection.
Supplied as bind values, single quotes in the values of attrData and medname won't be an issue, in terms of SQL Injection.
But the example I've provided is vulnerable through incorporating the colname variable into the SQL text, if we don't have some guaranteed that colname is "safe" to include in the statement.
So we need to make the assignment of a value to colname "safe".
Several approaches we can use do that. The most secure would be a "whitelist" approach. The code can ensure that only specific allowed "safe" values get assigned to colname, before colname gets included into the SQL text.
As a simple example:
String colname;
if (attributes.equals("someexpectedvalue") {
colname = "columnname_to_be_used";
} else if (attributes.equals("someothervalid") {
colname = "valid_columname";
} else {
// unexpected/unsupported attributes value so
// handle condition or throw an exception
}
A more flexible approach is to ensure that a backtick character doesn't appear in colname. In the example, the value of colname is being escaped by enclosing it in backticks. So, as long as a backtick character doesn't appear in colname, we will prevent a supplied value from being interpreted as anything other than as an identifier.
For a more generic (and complicated) approach to using hardcoded backtick characters, we could consider making use the supportsQuotedIdentifiers and getIdentifierQuoteString methods of java.sql.DatabaseMetaData class.
(In the OP code, we don't see the datatype of contents of attributes. We see a call to a method named replace, and the arguments that are supplied to that. Assuming that attributes is a String, and that's supposed to be a column name, it's not at all clear why we would have "space single quote space" in the string, or why we need to remove that. Other than this mention, this answer doesn't address that.)
I have a bean class which does maintain user data:
soppose I have created a postgresql DB table like this:
StringBuffer sqlStr = new StringBuffer();
sqlStr.append("CREATE TABLE Users ("
user_id bigint,
username character varying NOT NULL,
biography character varying NOT NULL
);
& I want to make a query command and inject my String data inside it:
sqlStr.append("INSERT INTO users(" +
"user_id, username, biography)" +
"\n\tVALUES (" + user.getID()+ "," + user.getUsername() + "," + user.getBiography()+");";
my problem is for example if the data coming from my method has quote or double quote or "," my command will become wrong suppose that the user biography is something like this :
hello, I'm Mr X an "IT Pro" ...
If I run my application and save the output inside a file called query.sql I can't use it because my query command is wrong because of quote & double quote, something like this:
INSERT INTO users(userid, username, biography)
VALUES(2, 'Mehdi', 'hello, I'm Mr X an "IT Pro" ..');
how Can I fix this problem ?
You should never ever use the above method for constructing SQL queries.
"Why not?" you ask, well; where to start. The classic example is Bobby Tables, the more general problem is SQL injection. This leaves your program open to attack but also to random failure - like the situation you describe.
Now, the solution. Always use PreparedStatement to construct your query. In your example
final String query = "INSERT INTO users(user_id, username, biography) VALUES (?,?,?)";
final PreparedStatement ps = con.prepareStatement(query);
ps.setInt(1, user.getID());
ps.setString(2, user.getUsername());
ps.setString(3, user.getBiography());
ps.executeUpdate();
A much nicer syntax to use with is the the SET syntax rather than the traditional VALUES syntax. The query would then look like
final String query = "INSERT INTO users SET user_id = ?, username = ?, biography = ?";
EDIT
The OP is building a query for a script file, not executing a query in the code.
There is a utility class in Apache Commons Lang, StringEscapeUtils. This has an escapeSql method. Looking at the source code, all this does is escape single quotes with another single quote.
This works if you build your queries with single quotes:
VALUES (" + user.getID()+ ",'" + user.getUsername() + "'...
So the query, once the example value is inserted will go from:
VALUES (10 ,'hello, I'm Mr X an "IT Pro"'...
Will become
VALUES (10 ,'hello, I''m Mr X an "IT Pro"'...
The apostrophe in "I'm" is now escaped and harmless.
Note that you obviously need to escape the values and not the query, so (assuming you have a static import for the class)
VALUES (" + user.getID()+ ",'" + escapeSql(user.getUsername()) + "'...
But does not escape other sql characters, percent signs for example.
This is really a stop-gap measure to make the code work while you come up with a more robust solution. And you should come up with a more robust solution.
Why dont you use PreparedStatement? That will also give you better performance as the SQL will be pre-compiled on DB side.
Or
You can escape the quotes using
String.replaceAll http://docs.oracle.com/javase/6/docs/api/java/lang/String.html#replaceAll(java.lang.String, java.lang.String)
I'm attempting to create a JDBC query with the following statement
String query = "SELECT COLUMN1,DATECOLUMN2 FROM tableName +
"where datediff(d,DATECOLUMN2,getdate()) <= 1";
st = conn1.createStatement();
rs = st.executeQuery(query); //receiving error here
I am receiving the following error message
java.sql.SQLException: "d" is not a recognized table hints option. If it is intended as a parameter to a table-valued function or to the CHANGETABLE function, ensure that your database compatibility mode is set to 90.
I'm sure the query isn't recognizing the datediff function for some reason I am not sure why since i was previously using HQL in the same application and retrieving the values.
In an attempt to use an alternative function I used
{fn TIMESTAMPADD( SQL_TSI_DAY, 1, CURRENT_TIMESTAMP)}
but it also failed I later on found that this is only used for Derby Database's
Can someone assist me in using the proper sql function to compare a date with the current date using JDBC
String query = "SELECT COLUMN1,DATECOLUMN2 FROM tableName "+
"where datediff(day,DATECOLUMN2,getdate()) <= 1";
You have a comma before from. Based on the error messages you are running this against SQL server.
String query = "SELECT COLUMN1,DATECOLUMN2 FROM tableName "
+" where datediff(d,DATECOLUMN2,getdate()) <= 1";
The comma after the "d" should be a dot:
where datediff(d.DATECOLUMN2,getdate())
--------------- ^ dot here
The posted snippet doesn't have a closing double quote between tableName and +, but I figure that is just a typo. However, in your real code, where precisely is the double quote? Is it directly after tablename, like this
String query = "SELECT COLUMN1,DATECOLUMN2 FROM tableName" +
or after the space that follows tablename, like this
String query = "SELECT COLUMN1,DATECOLUMN2 FROM tableName "+
It is very likely the former, because in that case the resulting query would look exactly the way as to cause the error you are getting. Take a look at this:
SELECT COLUMN1,DATECOLUMN2 FROM tableNamewhere datediff(d,DATECOLUMN2,getdate()) <= 1
You can see that where merges with the table name and datediff becomes an alias. What follows is interpreted as table hints. (You can specify table hints without WITH in older versions of SQL Server/older compatibility levels.) Consequently, SQL Server stumbles over d, as that is indeed an incorrect table hint.
String sqlStm = "SELECT * FROM TableName WHERE TableName MATCH '?'";
pst.setString(1, keyword.getText());
I am doing a full-text search on my database. When I use the above it doesnt execute the sql statement. However, if I were to change the program and give a value to match like this...
String sqlStm = "SELECT * FROM TableName WHERE TableName MATCH 'technology'";
The programme execute. But i want the search to be based on entered text in keyword JTextfield. is the formatting correct in the first line. does MATCH support pst.setString(). What should be the correct statement.
remove the single quote around the parameter, it will convert the parameter into a value. Parameter placeolder ? shouldn't be enclosed with single quotes.
String sqlStm = "SELECT * FROM TableName WHERE TableName MATCH ?";
pst.setString(1, keyword.getText());
How about this?
SELECT * FROM TableName WHERE TableName LIKE '%^technology$%'
or
SELECT * FROM TableName WHERE TableName REGEXP '^\\technology$'
I couldn't really find any article that says SQlite Like or regexp behaves differently than MySQL so... you may give that a try. If there is anything that differs please share as well.