Using RODBCext (and Teradata) my SQL query often need to be restricted and is done so with a where statement. However, this is not always required and it would be beneficial to not restrict, but I would like to use a single SQL query. (The actual query is more complex and has several instances of what I'm attempting to apply here)
In order to return all rows, using a wildcard seems like the next best option, but nothing appears to work correctly. For example, the sql query is:
SELECT *
FROM MY_DB.MY_TABLE
WHERE PROC_TYPE = ?
The following does work when passing in a string for proc_type:
sqlExecute(connHandle, getSQL(SQL_script_path), proc_type, fetch = TRUE)
In order to essentially bypass this filter, I would like to pass a wildcard so all records are returned.
I've tried proc_type set to '%', '*'. Also escaped both with backslashes and enclosed with double-quotes, but no rows are ever returned, nor are any errors produced.
You could use COALESCE to do this:
SELECT *
FROM MY_DB.MY_TABLE
WHERE PROC_TYPE = COALESCE(?, PROC_TYPE);
In the event that your parameter is NULL it will choose PROC_TYPE to compare to PROC_TYPE which will return everything.
As for your wildcard attempt you would have to switch over to an operator that can use a wildcard. Instead of =, LIKE for instance. I think you would end up with some oddball edge cases though depending on your searchterm and the data in that column, so the COALESCE() option is a better way to go.
Related
I have a simple query like this:
SELECT * FROM CUSTOMERS WHERE CUSTID LIKE '~' AND BANKNO LIKE '~'
The problem is, the customers-table might or might not contain the BANKNO column depending on circumstances I've no control over. If however BANKNO is not a column in CUSTOMERS, this query fails.
So my question is: it is possible to test if the BANKNO column exists and if so, to include it in the query and if not to exclude this column?
The query really has to be flexible.
A non-existent column in a SELECT to sqlite3 will always fail.
One option might be to put the "full" sql in a try block, and if it errors, execute the other sql.
Or, you could query PRAGMA table_info('CUSTOMERS') and interrogate the result to see if a column in question is in the database. Find the sqlite doc here https://www.sqlite.org/pragma.html#pragma_table_info.
I'm sure there are other options, but the bottom line is you need to know before the sql is executed that it contains only valid column names.
I have an SQLITE Database with the following tables
items(item_id,item_name,....);
tags(tag_id,tag_name);
items_tags(item_id,tag_id);
I'm using QSqlRelationalTableModel class to for the items table.
this class have this function QSqlTableModel::setFilter(const QString &filter);
The filter is a SQL WHERE clause without the keyword WHERE
for example: setFilter("item_name=arg");
what I want to do is to use the setFilter function to select only items with a specific tag/tags.
since I can only use the setFilter(QString &Filter) function which is basically a WHERE clause
I found this solution which I think is a bad one
I'll use this filter
setFilter(FilterString);
FilterString="item_id=arg1 or item_id=arg2 or item_id=argX or......"
the IDs will be obtained from this query
Query.prepare("select item_id from items_tags where tag_id=?");
the FilterString will be generated and incremented by a (do while loop) using Query.next() function that will loop over the resulted Query IDs
FilterString+="item=Query.value(item_id).toString();
and use like 2 if statements to determine when to add the or clause to the FilterString
this solution will definitely work but I think it's stupid because if there are many tagged items(say 5000) the Query string will contain 4999 or clause and another 5000 "id=x" so the Query will be more than 10000 characters long.
QString object can contain a lot more characters but is this Query will have a big impact on performance ?
what are the other alternatives, Even if it requires to switch to another DB like ORACLE or Mysql since SQLITE doesn't have many internal features
My R workflow now involves dealing with a lot of queries (RPostgreSQL library). I really want to make code easy to maintain and manage in the future.
I started loading large queries from separate .SQL files (this helped) and it worked great.
Then I started using interpolated values (that helped) which means that I can write
SELECT * FROM table WHERE value = ?my_value;
and (after loading it into R) interpolate it using sqlInterpolate(ANSI(), query, value = "stackoverflow").
What happens now is I want to use something like this
SELECT count(*) FROM ?my_table;
but how can I make it work? sqlInterpolate() only interpolates safely by default. Is there a workaround?
Thanks
In ?DBI::SQL, you can read:
By default, any user supplied input to a query should be escaped using
either dbQuoteIdentifier() or dbQuoteString() depending on whether it
refers to a table or variable name, or is a literal string.
Also, on this page:
You may also need dbQuoteIdentifier() if you are creating tables or
relying on user input to choose which column to filter on.
So you can use:
sqlInterpolate(ANSI(),
"SELECT count(*) FROM ?my_table",
my_table = dbQuoteIdentifier(ANSI(), "table_name"))
# <SQL> SELECT count(*) FROM "table_name"
sqlInterpolate() is for substituting values only, not other components like table names. You could use other templating frameworks such as brew or whisker.
I am working on a report, and for my data set i need to use an or statement. in SQL my query would look like:
SELECT recId, etc... FROM CustTrans
WHERE (CustTrans.Closed IS NULL AND CustTrans.Invoice IS NULL)
OR (CustTrans.Invoice IS NOT NULL)
I would translate this then into range like the following (stuck on the RecId field)
Value:
((CustTrans.Invoice == ‘’) && (CustTrans.Closed == ‘’) || (CustTrans.Invoice != ‘’))
I have found numerous places explaining that this is the proper syntax, although all of them are using the programmatic method of creating a query. I need to keep mine in the AOT so the customer can modify it later on if they want, and every combination of quotes, parens, and order still does not work. Sometimes AX will accept my range value string, but it doesn't do anything, and sometimes it will give me a random syntax error.
Is there a way to accomplish what I'm looking to do? have I missed some syntax, or does AX really not let you use OR on a query without a union and another view?
Thanks!
You can create a Query in the AOT and then over-ride the init method for the Query. Where you can put these complex SQL statements and get your work done.
I am trying to perform queries using the OR operator as following:
MapReduceResult result = riakClient.
mapReduce("some_bucket", "Name:c1 OR c2").
addMapPhase(new NamedJSFunction("Riak.mapValuesJson"), true).
execute();
I only get the 1st object in the query (where name='c1').
If I change the order of the query (i.e. Name:c2 OR c1) again I get only the first object in query (where name='c2').
is the OR operator (and other query operators) supported in the java client?
I got this answer from Basho engeneer, Sean C.:
You either need to group the terms or qualify both of them. Without a field identifier, the search query assumes that the default field is being searched. You can determine how the query will be interpreted by using the 'search-cmd explain' command. Here's two alternate ways to express your query:
Name:c1 OR Name:c2
Name:(c1 OR c2)
both options worked for me!