Identifier of a column from a specified table used in evaluations or as a search condition.A column of the array type cannot be an element in an expression except when used with the IS [NOT] NULL predicate.

An expression may contain a reference to an array member i.e., <array_name>[s], where s is the subscript of the member in the array <array_name>

The +, -, *, / characters used to calculate values

The || (“double-pipe”) operator used to concatenate strings

The reserved words NOT, AND and OR, used to combine simple search conditions to create complex conditions

The symbols =, <>, !=, ~=, ^=, <, <=, >, >=, !<, ~<, ^<, !>, ~> and ^>

[fblangref50-commons-predlike], [fblangref50-commons-predstartwith], [fblangref50-commons-predcontaining], [fblangref50-commons-predsimilarto], [fblangref50-commons-predbetween], [fblangref50-commons-isnotnull], IS [NOT] {TRUE | FALSE | UNKNOWN} and [fblangref50-commons-isnotdistinct]

Predicates used to check the existence of values in a set.The IN predicate can be used both with sets of comma-separated constants and with subqueries that return a single column.The [fblangref50-commons-exists], [fblangref50-commons-singular], [fblangref50-commons-quant-all], [fblangref50-commons-quant-anysome] predicates can be used only with sub-queries.

Numbers, or string literals enclosed in apostrophes or Q-strings, Boolean values TRUE, FALSE and UNKOWN, NULL

An expression, similar to a string literal enclosed in apostrophes, that can be interpreted as a date, time or timestamp value.Datetime literals can be strings of characters and numerals, such as TIMESTAMP '25.12.2016 15:30:35', that can be resolved as datetime value.

A string literal with a description of a desired datetime value that can be cast to a datetime type.For example 'TODAY', 'NOW'.

An internally-defined context variable

Declared local variable, input or output parameter of a PSQL module (stored procedure, stored function, trigger, or unnamed PSQL block in DSQL)

A member of an ordered group of one or more unnamed parameters passed to a stored procedure or prepared query

A SELECT statement enclosed in parentheses that returns a single (scalar) value or, when used in existential predicates, a set of values

The identifier of an internal, packaged, stored or external function in a function expression

An expression explicitly converting data of one data type to another using the CAST function (CAST (<value> AS <datatype>)).For datetime literals only, the shorthand syntax <datatype> <value> is also supported (DATE '2016-12-25').

Expressions using CASE and related internal functions

Bracket pairs (…​) used to group expressions.Operations inside the parentheses are performed before operations outside them.When nested parentheses are used, the most deeply nested expressions are evaluated first and then the evaluations move outward through the levels of nesting.

Clause applied to CHAR and VARCHAR types to specify the character-set-specific collation to use in string comparisons

Expression for obtaining the next value of a specified generator (sequence).The internal function GEN_ID() does the same.

Expression to change the time zone of a datetime.