Summary: in this tutorial, you will learn about PostgreSQL foreign key and how to add foreign keys to tables using foreign key constraints.. Introduction to PostgreSQL Foreign Key Constraint. > Have you tried WITH NULL AS ''? into PGSQL and I find the quotes very distracting. You could write your function definition with single-quotes just as well. One of the questions that invariably arises in these classes has to do with the case sensitivity of the technology in question. The CONCAT_WS function returns a combined string that is the combination of str_1, str_2, etc., separated by the separator.. PostgreSQL CONCAT_WS function example. Responses Re: Why are quotes required around table / column names in SQL statements? A foreign key is a column or a group of columns in a table that reference the primary key of another table.. The separator is a string that separates all arguments in the result string.. I spend a large proportion of my time teaching classes in a variety of open-source technologies — specifically, Ruby, Python, PostgreSQL, and Git. (When continuing an escape string constant across lines, write E only before the first opening quote.) The table that contains the foreign key is called the referencing table or child table. 11 Don’t use double quotes in PostgreSQL. PostgreSQL QUOTE_IDENT() function with Example : The PostgreSQL quote_ident function is used to make a given string with suitably double quoted, so as it can be used like an identifier in an sql statement string if required. replacing single quotes. You could write your function definition with single-quotes just as well. at 2001-04-03 01:25:45 from Lee Harr Input is of form 'ppp','aaa','bbb' I want it to be stripped of quotes to become ppp,aaa,bbb escaping the quote would work but it means I will have to do some... PostgreSQL › PostgreSQL - general For example, a typical WHERE clause may look like WHERE t_name = 'database'. The problem arises when the string constant contains many single quotes and backslashes. PostgreSQL also allows single quotes to be escaped with a backslash (\), so for example the same string could be written 'Dianne\'s horse'. So >> a null value for a field looks like "" > It should be ,, for NULL. An escape string constant is specified by writing the letter E (upper or lower case) just before the opening single quote, e.g., E'foo'. Dollar-quoting is a PostgreSQL-specific substitute for single quotes to avoid quoting issues inside the function body. As you probably understand, apostrophe (otherwise known as semi-quotes or single quotes) and quote symbols are used in Postgres and many programming languages to delineate text strings and string-based commands. > I suspect the solution is probably simple; yet, I can't get i I think you need two single quotes around the embedded sql string. Bruce Momjian <[hidden email]> writes: > Walter wrote: >> I have a problem using the copy command on a CSV file. The str_1, str_2, etc., are strings or any arguments that can be converted into strings.. Doubling every single quote and backslash makes the string constant more difficult to read and maintain. PostgreSQL also accepts “ escape ” string constants, which are an extension to the SQL standard. >> >> All of the values within the CSV are surrounded with quotation marks. PostgreSQL version 8.0 introduced the dollar quoting feature to make string constants more readable. 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