====== INSTR Function - PL/HQL ======

INSTR function returns the starting position of a substring within a string.

**Syntax**:

<code language="sql">
INSTR(string, substring [, position [, occurrence]]) 
</code>

**Notes**:

  * //position// specifies the staring position for search, the default is 1 (the beginning of //string//)
  * If //position// is negative INSTR counts and searches backward from the end of string
  * //occurrence// specifies which occurrence of //substring// to search, the default is 1 (finds the first occurrence)
  * If //string// is NULL the return value is NULL
  * if //string// is not NULL and //substring// not found the return value is 0

**Return Type:**

INT

**Example 1**:

Find the first occurrence starting from the beginning:

<code language="sql">
INSTR('abc', 'b')                      -- Result 2
</code>

**Example 2**:

Find the first occurrence starting from the 3rd position:

<code language="sql">
INSTR('abcabc', 'b', 3)                -- Result 5
</code>

**Example 3**:

Find the second occurrence starting from the 3rd position:

<code language="sql">
INSTR('abcabcabc', 'b', 3, 2)          -- Result 8
</code>

**Example 4**:

Find the first occurrence starting from the 3rd position from the end:

<code language="sql">
INSTR('abcabcabc', 'b', -3)            -- Result 5
</code>

**Example 5**:

Find the second occurrence starting from the 3rd position from the end:

<code language="sql">
INSTR('abcabcabc', 'b', -3, 2)         -- Result 2
</code> 

**Compatibility**: Oracle, IBM DB2 and Teradata.

**Version:** PL/HQL 0.3.11