Within these strings, the following rules apply:

• Double quotation marks delimit special identifiers referred to in SQL as delimited identifiers.
• Single quotation marks delimit character strings.
• Within a character string, to represent a single quotation mark or apostrophe, use two single quotation marks. (In other words, a single quotation mark is the escape character for a single quotation mark.)

  A double quotation mark does not need an escape character. To represent a double quotation mark, simply use a double quotation mark. However, note that in a Java program, a double quotation mark requires the backslash escape character.

  Example:-- a single quotation mark is the escape character -- for a single quotation mark VALUES 'Joe''s umbrella' -- in ij, you don't need to escape the double quotation marks VALUES 'He said, "hello!"' n = stmt.executeUpdate( "UPDATE aTable setStringcol = 'He said, \"hello!\"'");
• SQL keywords are case-insensitive. For example, you can type the keyword SELECT as SELECT, Select, select, or sELECT.
• SQL-style identifiers are case-insensitive (see ), unless they are delimited.
• Java-style identifiers are always case-sensitive.
• * is a wildcard within a selectExpression. See . It can also be the multiplication operator. In all other cases, it is a syntactical metasymbol that flags items you can repeat 0 or more times.
• % and _ are character wildcards when used within character strings following a LIKE operator (except when escaped with an escape character). See .
• Comments can be either single-line or multiline as per the SQL standard. Single-line comments start with two dashes (--) and end with the newline character. Multiline comments are bracketed, start with forward slash star (/*), and end with star forward slash (*/). Note that bracketed comments may be nested. Any text between the starting and ending comment character sequence is ignored.