Add position() function to V2 engine

[margarit-h]

Signed-off-by: Margarit Hakobyan margarith@bitquilltech.com

Description

Usage: The syntax POSITION(substr IN str) returns the position of the first occurrence of substring substr in string str. Returns 0 if substr is not in str. Returns NULL if any argument is NULL.

Argument type: STRING, STRING

Return type integer:

(STRING IN STRING) -> INTEGER

Example::

os> SELECT POSITION('world' IN 'helloworld')
fetched rows / total rows = 1/1
+-------------------------------------+
| POSITION('world' IN 'helloworld')   |
|-------------------------------------|
| 6                                   |
+-------------------------------------+

Issues Resolved

#1106

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.79%. Comparing base (43ceda1) to head (17bd91d).
Report is 404 commits behind head on 2.x.

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x    #1121      +/-   ##
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- Coverage     98.30%   95.79%   -2.51%     
- Complexity     3470     3473       +3     
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  Files           348      358      +10     
  Lines          8659     9326     +667     
  Branches        549      668     +119     
============================================
+ Hits           8512     8934     +422     
- Misses          142      334     +192     
- Partials          5       58      +53     

Flag	Coverage Δ
query-workbench	62.76% <ø> (?)
sql-engine	98.30% <100.00%> (+<0.01%)	⬆️

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[penghuo]

Returns 0 if substr is not in str? not -1?
what if POSITION('world' IN 'world')?

[margarit-h]

This function is the synonym of the LOCATE function. And works the same way in mySQL and legacy engine.
It returns 0, if substr in not in string like LOCATE and POSITION do in mySql and legacy engine.
POSITION('world' IN 'world') would return 1 as the first argument matches the given string (2nd arg) starting from the 1st position.

[dai-chen]

Thanks for the changes!