The following example uses the dollar-quoted string constant syntax with a tag: SELECT $message$I'm a string constant that contains a backslash \$message$ In this example, we did not specify the tag between the two dollar signs($). For example: select $$I'm a string constant that contains a backslash \$$ So if you seed the function with something like, PostgreSQL rocks, and tell it you want the first 10 characters of that string, the SUBSTRING() function will return PostgreSQL. Between the $tag$, you can place any string with single quotes (‘) and backslashes (\). The PostgreSQL SUBSTRING function returns a portion of a string. The following shows the syntax of the dollar-quoted string constants: Syntax: $tag$$tag$ PostgreSQL version 8.0 introduced the dollar quoting feature to make string constants more readable. Doubling every single quote and backslash makes the string constant more difficult to read and maintain. The problem arises when the string constant contains many single quotes and backslashes. If a string constant contains a backslash, you need to escape it by using another backslash. If you use an old version of PostgreSQL, one can prepend the string constant with E to declare the postfix escape string syntax and use the backslash \ to escape the single quote like this: select E'I\'m also a string constant' For example: select 'I''m also a string constant' When a string constant contains a single quote (‘ ), you need to escape it by doubling up the single quote. In PostgreSQL, you use single quotes for a string constant like this: select 'String constant' ISRO CS Syllabus for Scientist/Engineer Exam.ISRO CS Original Papers and Official Keys.GATE CS Original Papers and Official Keys.\s: whitespace character, +: at least one, *: zero or more and | means alternation.
#Postgresql substring plus#
When names should be split whenever they are separated by comma plus optional whitespace or with an y surrounded by mandatory whitespace the following regular expression will work: \s*,\s*|\s+y\s+ I am not familiarized with regex sintax, I have found this example in the PostgreSQL documentation. Then I tried this option: select t2.name2 from (regexp_split_to_array(t.shipnames, E'\\s+') as name2 from ships t) t2īut It doesn't work because not every record has the same length so some are solved like. With several changes in the #"pattern#" to find the white spaces and get the second name. I have tried this option: select substring(t.shipsnames from '%#",_y#"%' for '#') as name2 from ships t The three named records look like this: Nuestra Señora del Rosario, Santo Domingo y San José Where t2.esp3 like '% y %' and t2.espectro like '%, %' Select "Id" as id, strpos(shipname, ', ') as posinic, strpos(shipname, ' y ') as posfin,shipname as espectro, shipname3 as espectro3 from ships) t)t2 (esp3, espectro, espectro3, id) Select substring(t.espectro, t.posfin)::varchar as esp3, t.espectro,t.espectro3,t.id from(
Select strpos(shipname, ',') as posicion,shipname as espectro from ships) t ` and third `select t2.esp3,t2.espectro,t2.espectro3, t2.id from( Where t2.esp2 like '% y %' and t2.espectro not like '%, %' Īnd c) three names: I could get first select substring(t.espectro,1,t.posicion) from( Select "Id" as id, strpos(shipname, ', ') as posinic, strpos(shipname, ' y ') as posfin,shipname as espectro, shipname2 as espectro2 from ships) t)t2 (esp2, espectro, espectro2, id) Select substring(t.espectro, t.posfin)::varchar as esp2, t.espectro,t.espectro2,t.id from( Where t2.esp1 not like '%, %'`) and for the second name (`select t2.esp1,t2.espectro,t2.espectro1, t2.id from( Select "Id" as id, strpos(shipname, ', ') as posinic, strpos(shipname ' y ') as posfin,shipname as espectro, shipname1 as espectro1 from ships) t)t2 (esp1, espectro, espectro1, id) Select substring(t.espectro,1, t.posfin)::varchar as esp1, t.espectro,t.espectro1,t.id from( Select "Id" as id, strpos(shipname, ', ') as posinic, strpos(shipname, ' y ') as posfin,shipname as espectro, shipname1 as espectro1 from ships) t)t2 (esp1, espectro, espectro1, id)ī) two names select t2.esp1,t2.espectro,t2.espectro1, t2.id from( Select substring(t.espectro, t.posfin)::varchar as esp1, t.espectro,t.espectro1,t.id from( I have a column that stores ship names througout the ship's life and I want to split them into three columns.Ī) Only one name select t2.esp1,t2.espectro,t2.espectro1, t2.id from( I've been struggling with this query trying solutions found in this forum, but I can't go on.