ltfce - All mode's compatibility functions and operators.
Features compatible with all mode are provided. Functions and operators are created under lt_catalog. The table below lists features that can be used in all mode.
Table F.26. Functions
|
Item |
Overview |
|---|---|
|
DATABASE |
Return current schema as current database |
|
LOCATE |
Return the position of the substring in the string |
Table F.27. Operator type compatibility
|
Item |
|---|
|
LEFTARG:int2 RIGHTARG:text |
|
LEFTARG:int4 RIGHTARG:text |
|
LEFTARG:int8 RIGHTARG:text |
|
LEFTARG:text RIGHTARG:int2 |
|
LEFTARG:text RIGHTARG:int4 |
|
LEFTARG:text RIGHTARG:int8 |
|
LEFTARG:text RIGHTARG:numeric |
|
LEFTARG:numeric RIGHTARG:text |
DATABASE
LOCATE
Description
Synonym for current_schema(). The concept of schema is similar to that of database in MySQL. You can specify the current schema by setting the search_path.
Syntax
database() RETURNS text
General rules
Returns the name of the schema that is first in the search path (or a null value if the search path is empty).
Like mysql,This is the schema that will be used for any tables or other named objects that are created without specifying a target schema.
Example
lightdb@lt_test=# select database();
database
----------
public
(1 row)
Description
Return the position of the first occurrence of substring.
Syntax
LOCATE(substr TEXT,str TEXT) returns INTEGER
LOCATE(substr TEXT,str TEXT,POS INTEGER) returns INTEGER
General rules
The first syntax returns the position of the first occurrence of substring substr in string str.
The second syntax returns the position of the first occurrence of substring substr in string str, starting at position pos.
Returns 0 if substr is not in str.
Returns NULL if any argument is NULL.
Example
In the following example,position of 'bar' in 'foobarbar', starting at position 5. is returned.
SELECT LOCATE('bar', 'foobarbar', 5);
locate
--------
7
(1 row)
Add type overloading between text and Numeric Types(int2, int4, int8, numeric) for operators such as '+', '-', '*', '/', '<', '<=', '>', '>=', '=', '<>' and '%'.
Example
With it, you can directly add '1.1'::text with 1.
lightdb@test=# select '1.1'::text+1;
?column?
----------
2.1
(1 row)
When in Oracle or MySQL compatible type (see lightdb_syntax_compatible_type), base on the rule that 'unknown' can convert to 'text' in some situations (see Chapter 10 for details), you can directly add '1.1' with 1.
lightdb@test=# select '1.1'+1;
?column?
----------
2.1
(1 row)