$mysqli->close(); ?> 

Assembling an SQL statement in this fashion is sometimes known as “Dynamic SQL” . 

## 9.5 Expressions 

This section lists the grammar rules that expressions must follow in MySQL and provides additional information about the types of terms that may appear in expressions. 

## Expression Syntax 

•Expression Syntax 

•Expression Term Notes 

•Temporal Intervals 

The following grammar rules define expression syntax in MySQL. The grammar shown here is based on that given in the sql/sql_yacc.yy  file of MySQL source distributions. For additional information about some of the expression terms, see Expression Term Notes. 

expr : expr  OR expr | expr  || expr | expr  XOR expr | expr  AND expr | expr  && expr | NOT expr | ! expr | boolean_primary  IS [NOT] {TRUE | FALSE | UNKNOWN} | boolean_primary boolean_primary : boolean_primary  IS [NOT] NULL | boolean_primary  <=> predicate | boolean_primary comparison_operator predicate | boolean_primary comparison_operator  {ALL | ANY} ( subquery ) | predicate comparison_operator : = | >= | > | <= | < | <> | != predicate : bit_expr  [NOT] IN ( subquery ) | bit_expr  [NOT] IN ( expr  [, expr ] ...) | bit_expr  [NOT] BETWEEN bit_expr  AND predicate | bit_expr  SOUNDS LIKE bit_expr | bit_expr  [NOT] LIKE simple_expr  [ESCAPE simple_expr ] | bit_expr  [NOT] REGEXP bit_expr | bit_expr bit_expr : bit_expr  | bit_expr | bit_expr  & bit_expr | bit_expr  << bit_expr | bit_expr  >> bit_expr | bit_expr  + bit_expr | bit_expr  - bit_expr | bit_expr  * bit_expr | bit_expr  / bit_expr | bit_expr  DIV bit_expr | bit_expr  MOD bit_expr 

