Here is the Merchant Center Query Language grammar reference (in regular expression notation):
Query -> SelectClause FromClause? WhereClause? OrderByClause? LimitClause?
SelectClause -> SELECT FieldName (, FieldName)*
FromClause -> FROM TableName
WhereClause -> WHERE Condition (AND Condition)*
OrderByClause -> ORDER BY Ordering (, Ordering)*
LimitClause -> LIMIT PositiveInteger
Condition -> FieldName Operator Value | FieldName BETWEEN Value AND Value
Operator -> = | != | > | >= | < | <= | <> | IN | NOT IN |
CONTAINS ANY | CONTAINS ALL | CONTAINS NONE | DURING |
LIKE | NOT LIKE | REGEXP_MATCH | NOT REGEXP_MATCH
Value -> Number | NumberList | String | StringList | Function
Ordering -> FieldName (ASC | DESC)?
FieldName -> [a-z] ([a-zA-Z0-9._])*
TableName -> [A-Z] ([a-zA-Z_])*
StringList -> ( String (, String)* )
NumberList -> ( Number (, Number)* )
PositiveInteger -> [1-9] ([0-9])*
Number -> -? [0-9]+ (. [0-9] [0-9]*)?
String -> (' Char* ') | (" Char* ")
Function -> LAST_14_DAYS | LAST_30_DAYS | LAST_7_DAYS |
LAST_BUSINESS_WEEK | LAST_MONTH | LAST_WEEK_MON_SUN |
LAST_WEEK_SUN_SAT | THIS_MONTH | THIS_WEEK_MON_TODAY |
THIS_WEEK_SUN_TODAY | TODAY | YESTERDAY?indicates an optional element.*means zero or more;+means one or more.(xxxxxx)indicates a grouping.[a-z0-9]signifies character ranges.|stands for "or".