要使用表子查询，需要使用SQL操作符将嵌入式查询与布尔表达式组合在一起。
To use a table subquery, you need to use an SQL operator to combine the embedded query with a Boolean expression.
当一个表达式被赋值时，每个操作符将会被应用于其周围所有项所代表的数值。
When an expression is evaluated, each operator is applied to the data values represented by the surrounding terms.
如果表达式包含括号，但不包含操作符，则存在需要求值的函数。
If the expression contains parentheses but no operators, there is a function here that needs to be evaluated.
where子句包含由OR操作符联结的两个表达式，这意味着对于特定行，如果任一表达式值为TRUE，则将删除该行。
The WHERE clause contains two expressions that are joined by the or operator, which means that if either expression evaluates as TRUE for a specific row, that row will be deleted.
您可以连接表1中显示的元素(以及其他操作符)并加以组合使用，从而构建(非常)复杂的正则表达式。
You can string together the primitives in Table 1 (and other operators) and use them in combination to build (very) complex regular expressions.
以上表达式综合运用了字符分组，贪婪操作符、回溯，以及最小化组团来匹配嵌套标签。
The above expression combines character groups, greedy operators, back-tracking, and atomic groups to match nested tags.
正则表达式通过元字符加强的字符和操作符构建。
Regular expressions are built from characters and operators, augmented by metacharacters.
注意：当索引表达式被用于关系表达式，或作为某个操作符类函数的参数时，查询优化器将考虑使用函数索引。
Note: the query optimizer considers using a functional index when the index expression is used in a relational expression or as an argument to one of the operator class functions.
转换过程包括用下面的算法读入中缀表达式的操作数、操作符和括号。
The conversion process involves reading the operands, operators, and parentheses of the infix expression using the following algorithm.
W3Eval的数学表达式由数字、变量、操作符、函数和括号组成。
Mathematical expressions in W3Eval are built of Numbers, variables, operators, functions, and parentheses.
如果不喜欢使用这么长的字符串连接语句，另一种方法是使用字符串格式操作符，可以使用下面这样的表达式。
If you prefer not to use a long string concatenation statement like this, an alternative is to use the string formatting operator which enables you to have an expression like.
在后缀表达式中，不需要括号，而且操作符的优先级也不再起作用了。
In postfix notation, the need for parentheses is eliminated and the priority of the operators is no longer relevant. You can use the following algorithm to evaluate postfix expressions.
不可以用操作符、逗号或闭括号作为表达式的开始符。
Expressions must not begin with an operator, comma, or closing parenthesis.
不可以用操作符、函数、逗号或开括号作为表达式结束符。
Expressions must not end with an operator, function, comma, or opening parenthesis.
可以使用布尔操作符(AND,OR,NOT)组合这些表达式(AND, OR, NOT)。
You can combine such expressions with Boolean operators (AND, or, NOT).
正则表达式非常强大；可供使用的操作符的数量庞大，种类繁多。
Regular expressions are extremely powerful; the number and kind of operators and techniques you can command are enormous.
表达式由数据结构、绑定的变量（即具有值的变量）、数学操作符和函数调用组成。
The expression is composed of data structures, bound variables (that is, those with a value), mathematical operations and function calls.
清单15对一个变量应用decltype操作符，演示对表达式使用这个操作符的方法。
Listing 15 applies the decltype operator on a variable and shows the usage of the operator with an expression.
有效的操作符是+，-，*，/，每一个操作数是一个整数或者是一个表达式。
Valid operators are +, -, *, /. Each operand may be an integer or another expression.
表达式是数值，变量和操作符的组合。
An expression is a combination of values, variables, and operators.
交替操作符（|）匹配前置或后置表达式。 它必须匹配前一个或后一个表达式之一。
The alternation operator (|) matches either the preceding or following expression.
简单地说，优先级决定了有多个操作符的表达式如何对操作数分组。
Simply put, precedence stipulates how operands are grouped in expressions with multiple operators.
在进行匹配时，要用m//操作符来标识这些正则表达式（有时是可选的），而当匹配并替换时，则要用 s/// 操作符来 标识它们。
They are marked by the m// operator (sometimes optional) when matching, and by the s/// operator when matching and replacing.
在复合表达式中，操作数和操作符的结合方式决定了整个表达式的值。
In a compound expression, the way in which the operands are grouped to the operators may determine the result of the overall expression.
下列操作符与GNU正则表达式库兼容。
The following operators are provided for compatibility with the GNU regular expression library.
一个值为包括空格的字符串的C表达式，代表定义包含已初始化的只读数据段的汇编程序操作符。
C expression whose value is a string, including spacing, containing the assembler operation to identify the following data as read-only initialized data.
操作符允许一个过滤器使用与Perl兼容的正则表达式（PCRE）。
The "matches" operator allows a filter to apply to a specified Perl-compatible regular expression (PCRE).
也就是说，优先级和结合性决定了表达式的哪个部分用作哪个操作符的操作数。
That is, precedence and associativity determine which part of the expression is the operand for each of the operators in the expression.
也就是说，优先级和结合性决定了表达式的哪个部分用作哪个操作符的操作数。
That is, precedence and associativity determine which part of the expression is the operand for each of the operators in the expression.
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