I am using lua script
https://github.com/clofresh/mysql-proxy-cache to cache the select query.
But there is a problem with the way it is detecting select statement.
It is using following code
return query:sub(1,6):lower() == 'select'
This will not work if select query is nested in (). Example:
(SELECT * from tbl_name);
Is there a way to remove extra () in mysql proxy ?
or Is there a better way to detect select query?
I would try to write a normalizing script using the String Library that detect common patterns and replaces them with equivalent normalized sql.
One example is your parenteses but also queries where the where parts have been moved around could benefit from this.
The queries are actually inside of the the parentheses, not inside of a string? That shouldn't parse correctly, even with a plug in. If it is in a string then simply use :sub(2, 7), however, if it is not, then put it inside of a string. Create a function that basically reproduces the function, except puts it in a string, e.g.:
function mysqlQuery(mysqlString)
loadstring(mysqlString)();
return mysqlString;
end
mysqlQuery("SELECT * from tbl");
Related
I am forced to use raw query with the Knex, since there is an issue with the union
One query, is not that bad. But now I have other type of issue.
All other Knex queries (non raw ones), they simply return an array with the results
For example:
knex('user_subscription_plan')
.select('*')
.where('paused_days', '>', 91)
.where('status', 'N_PAUSED')
will return an array, empty of there is no results.
However, if I run raw query, for example:
mySqlClient.raw('select * from user')
it will return an array, with two arrays inside it.
First one is the normal result, while other one contains some catalogue definitions.
That interferes with my logic. At the end of each call to knex, I have:
if (result.length > 0) {
// send email
}
Now, when I run the raw Query, the result is always greater then zero.
How can I tell Knex not to send the catalogue definitions, in other words, just send results back, exactly like it does on non raw queries?
According to https://github.com/knex/knex/issues/1802 there is no way around it, just do
mySqlClient.raw('select * from user')[0]
You should do it like #horatiu-jeflea answered.
Though we could add some way to knex to tell that also result of raw query should be parsed with default result parser. To make that way to appear in knex you could open feature request to its github issues.
Also there is https://knexjs.org/#Installation-post-process-response which you should be able to override to handle your raw query results are post processed.
If you want to get the same result as the select result, use select and pass your raw query as an argument without "SELECT" keyword. In your example, instead of doing:
mySqlClient.raw('select * from user')
You should do:
mySqlClient.select( mySqlClient.raw(' * from user') )
I have a odd situation where I would like to phrase a variable inside an SQL string. Basically ODBC will return a query with a string, in that string there will be an Asterisk variable and I need that phrased and passed back to SQL. For example (pointless code but showing the example)-
exten => s,n,Set(QUERY=${ODBC_GET_QUERY(${EXTEN})})
The SQL query in func_odbc.conf is SELECT query FROM tablea WHERE number = ${ARG1}
Now QUERY will look like to = ${DIALED}, ${DIALED} being a asterisk variable (I will make it 17005551212 for example) I need that phrased so I end up with -
exten => s,n,Set(ALLOWED=${ODBC_GET_ALLOWED(${QUERY})})
The SQL query in func_odbc.conf would be SELECT allowed FROM tableb WHERE ${ARG1} so the SQL query would resolve to SELECT allowed WHERE to = 17005551212.
Before I dive into this and re-invent the wheel, is it possible or even allowed? I have actually not tried it yet. I know in a Set() statement it will phrase a variable inline, but is there a way to phrase variable that is in a variable when its returned via ODBC? Thanks!
Please read carefully source code.
Func odbc use prepair call. So it will not work for your example just becuase prepair do not allow do that.
In general you can substitute variables. Example 1 WILL work ok.
Workaround - use mysql EXEC.
I am working on a problem where I need to add an OR clause to a set of existing conditions. The current conditions are built in a hash in a method and at the end, they are used in the where clause. Here is a simplified example:
...
conds.merge!({:users => {:archived => false}})
Model.where(conds)
I am trying to add an OR clause to the current set of conditions so it would be something like '(conditions) OR new_condition'. I'd like to add the OR statement without converting each addition to the conds hash into a string. That would be my last option. I was hoping someone has done something like this before (without using Arel). I seem to recall in Rails 2 there was a way to parse a conditions hash using a method from the model (something like Model.some_method(conds) would produce the where clause string. Maybe that would be a good option to just add the OR clause on to that string. Any ideas are appreciated. Thank you for your help!
I found a way to do what I needed. Instead of changing all of the conditions that I am building, I am parsing the conditions to SQL using sanitize_sql_for_conditions. This is a private method in ActiveRecord, so I had to put a method on the model to allow me to access it. Here is my model method:
def self.convert_conditions_hash_to_sql(conditions)
self.sanitize_sql_for_conditions(conditions)
end
So, once I convert my conditions to text, I can add my OR clause (along with the appropriate parentheses) to the end of the original conditions. So, it would go something like this:
Model.where('(?) OR (model.type = ? AND model.id IN(?))', Model.convert_conditions_hash_to_sql(conds), model_type, model_id_array)
I have a string returned from a function "'aa','bb','cc',..."(the function uses GROUP_CONCAT). I want to use this as a condition in the IN clase of mysql.
SELECT name,class,comment
FROM vwstudent v
WHERE name IN (select func())
I want the query to act like
SELECT name,class,comment
FROM vwstudent v
WHERE name IN ('aa','bb','cc','dd',..)
I assume ('aa','bb','cc','dd',..) is acting as a whole string here and isn't generating any result. What can I do to run this query error less.
I'm not sure if it'll help. But you might be able to hack something together by using PREPARE and EXECUTE as described here: How To have Dynamic SQL in MySQL Stored Procedure
... but that's completely new to me. I've never used anything like that in MySQL.
I need to take a MySQL query and insert a string before each table name. The solution doesn't need to be one line but obviously it's a regex problem. It will be implemented in PHP so having programming logic is also fine.
Rationale and Background:
I'm revamping my code base to allow for table prefixes (eg: 'nx_users' instead of 'users') and I'd like to have a function that will automate that for me so I don't need to find every query and modify it manually.
Example:
SELECT * FROM users, teams WHERE users.team_id = teams.team_id ORDER BY users.last_name
Using the prefix 'nx_', it should change to
SELECT * FROM nx_users, nx_ teams WHERE nx_ users.team_id = nx_ teams.team_id ORDER BY nx_ users.last_name
Obviously it should handle other cases such as table aliases, joins, and other common MySQL commands.
Has anybody done this?
How big of a code base are we talking about here? A regular expression for something like this is seriously flirting with disaster and I think you're probably better off looking for every mysql_query or whatever in your code and making the changes yourself. It shouldn't take more than the hour you'd spend implementing your regex and fixing all the edge cases that it will undoubtedly miss.
Using a regex to rewrite code is going to be problematic.
If you need to dynamically change this string, then you need to separate out your sql logic into one place, and have a $table_prefix variable that is appropriately placed in every sql query. The variable can then be set by the calling code.
$query = "SELECT foo from " . $table_prefix . "bar WHERE 1";
If you are encapsulating this in a class, all the better.
This example does not take into consideration any escaping or security concerns.
First off, regular expressions alone are not up to the task. Consider things like:
select sender from email where subject like "from users group by email"
To really do this you need something that will parse the SQL, produce a parse tree which you can modify, and then emit the modified SQL from the modified parse tree. With that, it's doable, but not advisable (for the reasons Paolo gave).
A better approach would be to grep through your source looking for either the table names, the function you use to sent SQL, the word from, or something like it at script something to throw you into an editor at those points.