Fix DISTINCT with object values in SELECT and SEARCH queries

[Copilot]

Description

DISTINCT operations failed when comparing object values, treating all objects as identical due to [object Object] string coercion. Additionally, SELECT COLUMN DISTINCT did not apply distinct filtering to extracted values.

var data = [{a:1}, {a:2}, {a:1}];

// Before: returned 1 item (incorrect)
alasql('SELECT DISTINCT _ FROM ?', [data]);
// After: returns 2 items (correct)

// Before: returned [{a:1}] (incorrect) 
alasql('SELECT COLUMN DISTINCT _ FROM ?', [{a:1}, {b:2}, {a:1}]);
// After: returns [{a:1}, {b:2}] (correct)

Changes

Core Fix (src/38query.js)

• doDistinct: Use JSON.stringify() for object comparison instead of default string coercion

Modifier Enhancement (src/40select.js)

• modify COLUMN case: Apply distinctArray when query has distinct flag

Test Coverage (test/test167B.js)

• Added tests for object DISTINCT with same structure
• Added tests for object DISTINCT with different structures
• Added tests for primitive value DISTINCT
• Verified consistency between SELECT DISTINCT *, SELECT COLUMN DISTINCT _, and SEARCH DISTINCT(/)
• Converted tests to use arrow functions for synchronous test cases (removed unnecessary async callbacks)

Checklist

• Tests added for new functionality
• All tests pass
• No security vulnerabilities introduced
• Code formatting passes Prettier validation

[!WARNING]

Original prompt

---

This section details on the original issue you should resolve

<filter_complete></filter_complete>

<issue_title>Fix SEARCH DISTINCT function and SELECT DISTINCT functions</issue_title>
<issue_description>There are some problems with this operator to be fixed
</issue_description>

<agent_instructions>Please make a test file called test167B.js verifying if this issue is still a problem.

If it is a problem try to solve it.

If you need to update the grammar of alasql, then please do small precice changes to alasqlparser.jison and then run yarn jison && yarn test</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@mathiasrw Can you describe the problems a bit more? @agershun The result of these two functions should be the same, and it seems that now it is a same:

var data = [{a:1},{a:2},{a:1}];

var res1= alasql('SELECT * FROM ?',[data]);
var res2= alasql('SELECT DISTINCT * FROM ?',[data]);
var res3= alasql('SELECT COLUMN DISTINCT _ FROM ?',[data]);
var res4= alasql('SEARCH DISTINCT(/) FROM ?',[data]);

You can try this example in jsFiddle
</comment_new>
<comment_new>@mathiasrw
a) how come we use the _in the column distinct?

b) if you change the middle data to b:2 I would expect [{a:1},{b:2}] from res3 but get only a:1 http://jsfiddle.net/dw6eLu8h/2/
</comment_new>
<comment_new>@agershun
_ is a original object from the source array (reference), where * is a copy property by property.

For example:

    SET @data = @[{a:1},{a:2}];
    SELECT a FROM @data;
    -- [{a:1},{a:2}]
    SELECT _ FROM @data;
    -- [{_:{a:1}},{_:{a:2}}]
    SELECT  FROM @data; -- equivalent of SELECT  COLUMN _ FROM @data;
    -- [{a:1},{a:2}]

   SET @arr = @[1,2,3];
   SELECT * FROM @arr;
   -- should be  Error because this is not an object
    SELECT _ FROM @arr
    -- [{_:1},{_:2},{_:3},]
    SELECT FROM @arr
     -- [1,2,3]
    SELECT FROM @arr ORDER BY _ DESC
    -- [3,2,1]

</comment_new>
<comment_new>@mathiasrw
Ahh - ok

Did you check out b) ?
</comment_new>

• Fixes Fix SEARCH DISTINCT function and SELECT DISTINCT functions #167

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Fix SEARCH DISTINCT function and SELECT DISTINCT functions</issue_title>
<issue_description>There are some problems with this operator to be fixed
</issue_description>

<agent_instructions>Please make a test file called test167B.js verifying if this issue is still a problem.

If it is a problem try to solve it.

If you need to update the grammar of alasql, then please do small precice changes to alasqlparser.jison and then run yarn jison && yarn test</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@mathiasrw Can you describe the problems a bit more? @agershun The result of these two functions should be the same, and it seems that now it is a same:

var data = [{a:1},{a:2},{a:1}];

var res1= alasql('SELECT * FROM ?',[data]);
var res2= alasql('SELECT DISTINCT * FROM ?',[data]);
var res3= alasql('SELECT COLUMN DISTINCT _ FROM ?',[data]);
var res4= alasql('SEARCH DISTINCT(/) FROM ?',[data]);

You can try this example in jsFiddle

@mathiasrw a) how come we use the `_`in the column distinct?

b) if you change the middle data to b:2 I would expect [{a:1},{b:2}] from res3 but get only a:1 http://jsfiddle.net/dw6eLu8h/2/

@agershun _ is a original object from the source array (reference), where \* is a copy property by property.

For example:

    SET @data = @[{a:1},{a:2}];
    SELECT a FROM @data;
    -- [{a:1},{a:2}]
    SELECT _ FROM @data;
    -- [{_:{a:1}},{_:{a:2}}]
    SELECT  FROM @data; -- equivalent of SELECT  COLUMN _ FROM @data;
    -- [{a:1},{a:2}]

   SET @arr = @[1,2,3];
   SELECT * FROM @arr;
   -- should be  Error because this is not an object
    SELECT _ FROM @arr
    -- [{_:1},{_:2},{_:3},]
    SELECT FROM @arr
     -- [1,2,3]
    SELECT FROM @arr ORDER BY _ DESC
    -- [3,2,1]

@mathiasrw Ahh - ok

Did you check out b) ?

• Fixes Fix SEARCH DISTINCT function and SELECT DISTINCT functions #167

---

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[mathiasrw]

@copilot

Run yarn test-format-all
yarn run v1.22.22
$ prettier --list-different '{.,src,test}/*.{js,ts,json}' || (echo 'Please correct file formatting using yarn format-all and try again.' && exit 1)
test/test167B.js
Please correct file formatting using yarn format-all and try again.
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
Error: Process completed with exit code 1.

[Copilot]

@copilot

Run yarn test-format-all
...

Fixed formatting issues. Tests now use arrow functions without async done callbacks. Fixed in commit 7d43b9d.

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