what axxess keys used for

references this record, a foreign key field is used to record this logical primary key,This is equivalent to a property in the object that records a pointer to the object. In this case, if you use the business primary key, especially the composite business primary key, you will be in trouble. MostThe worst case is that when you need to modify the value of this business primary key, all the associations will be disordered-in traditional C/S applicatio

Tags: scene data. com Get server name statement-o imagecursors cursor, I think most people have used it in SQL Server. Cursors can still be used when the amount of data in a table is not too large, since cursors are the easiest way to iterate through each row of data in a table. But what happens if you use a cursor to loop a table that doesn't have a primary key

How do you choose what you usually choose between the foreign key and the table link? Between Foreign key and table Link Reply content: How do you chooseBetween Foreign key and table Link Let's see the scenario. For example, if you have a table to store product data and another table to store the product type, there is no foreign key at this time.If you have a table that stores order data, another table that stores customer information, a tab

How do you choose the usual Between the outer key and the table link Reply content: How do you choose the usualBetween the outer key and the table link Look at the situation, for example, you have a table to store product data, another table for the product type, this time with foreign keys and nothingIf you have a table that holds order data, another table that stores customer information, a table that stores product information, and a table

primary key is a selected candidate key. I understand what is a candidate keyTake a look at the question firstIn the SQL Server database, there is a student information table as follows. In this table, the attribute set that cannot be used as the candidate key is () (select one)Student ID name gender age Division Major20020612 Li Hui male 20 Computer Software Development20060613 Zhang mingnan 18 Computer S

files are open.4. Ctrl+2,l: Assigning a value to a local variableDuring development, I often write methods, such as calendar.getinstance (), and then assign the results of a method to a local variable by ctrl+2 shortcut keys. This saves me the input class name, the variable name, and the time the declaration was imported. The ctrl+f effect is similar, but the effect is to assign the result of the method to a field in the class.5. Alt+shift+r: Renamin

. Control-q: Go back to the last editing place. This shortcut is also used when you jump in the code. Especially if you drill too deep. Forget what you were doing in the first place. CONTROL-SHIFT-G: Search for references in Workspace (reference). This is the premise of refactoring. For the method, the function of this hotkey is exactly the opposite of F3. It puts you in the stack of methods. Up to find

Before using eclipse to write Java, there are several commonly used shortcut keys, such as delete the current line, insert a blank line below the current line, move up/down the current line and so on, to xcode how can not find these shortcuts, always feel that Xcode comes with the shortcut key is not strong enough, Until today we know that without a third-party plug-in, you can fully implement these functio

A week did not knock code, shortcut keys and forget, it seems necessary to summarize, for yourself to see. (commonly used, not commonly used not to write, write also can't remember)Quick fix:ctrl+1Word completion:alt+/Full Project Search:ctrl+hDelete Row:ctrl+d is very useful, without the mouse dragInsert one line on the current line:ctrl+shift+enterInsert one li

the Foreign key table, the main table is also called the primary key table, the appearance, the column is also called the field. so at the time of design. Add a foreign key to table 1, which is the Number field in table 2. So table 1 is the main table, and table 2 is the child table . Your master-slave relationship is upside down. In your diagram, table 1 is really the main table. Table 2 is a child table, but is not called to table 1 to add a foreign key, but to table 2 to add a foreign key,

An eclipse-level developer sums up what he considers to be the most useful but less well known shortcut key combination. These combinations make it easier to browse through the source code and improve the overall efficiency and quality of the development.1. Ctrl+shift+r: Open ResourcesThis may be the most time-saving of all shortcut key combinations. This set of shortcuts allows you to open any file in your workspace, and you only need to press the fi

column is also called the field.so in the design, you add a foreign key to table 1, the foreign key is the Number field in table 2, then table 1 is the main table, table 2 is the child table .Your master-slave relationship is upside down. In your diagram, table 1 is really the main table, table 2 is a child table, but not called to add a foreign key to table 1, but instead of adding a foreign key to table 2, table 2, the Number field is called the foreign key, it is the table 1 Number field of

an eclipse-level developer sums up what he considers to be the most useful but less well known shortcut key combination. These combinations make it easier to browse through the source code and improve the overall efficiency and quality of the development. 1. Ctrl+shift+r: Open Resources This may be the most time-saving of all shortcut key combinations. This set of shortcuts allows you to open any file in your workspace, and you only need to press the

Have you just started using Xcode to find the shortcuts for the previously familiar development environment? How to run quickly, stop, edit and so on, are different. Quickly mastering these shortcuts can provide the efficiency of development.In fact, the shortcut keys in the Xcode toolbar are marked with, but some symbols and your keyboard symbols do not match up. The shortcut keys in the following toolbar

correspond to the hierarchy of the Navigator, which makes it easier to organize information.If this affects speed, turn it off.　　3. F3: Open the Declaration (opening declaration).Alternatively, use Declaration Tab (in Java view mode, select Windows–> Show view-> Declaration).When you select a method in the code and press the button, it will show the entire method in the Declaration box.　　4. Alt-left arrow: Back in navigation history (Navigation).Just like a Web browser's Back button, it is espe

button, it is especially useful after jumping with F3. (Used to return to the original compiled place)5. Alt-right Arrow: Navigate the history forward. 6. Control-q: Go back to the last editing place. This shortcut is also used when you jump in the code. Especially when you're too deep, and forget what you were doing in the first place. 7. CONTROL-SHIFT-G: S

can use the mouse to select a window when the drop-down window appears. The second method is recommended. Press "Alt" + "Tab" to move the selection box to the application icon of the window to be switched, then, press "super" + "'" to switch between the windows opened by this application. Note: "'" is the key above the tab key. No matter which keyboard layout you use, the key used for switching is always the one on the tab, so it may not be. If your

What is a foreign key A foreign key (FK) is one or more columns that are used to establish and strengthen a link between two table data. You can create a link between two tables by adding one or more columns that hold the primary key values in the table to another table. This column becomes the foreign key of the second table. Why foreign keys are

Frequently Used shortcut keys for Fedora GNOME In Fedora, to get the best GNOME desktop experience, you need to understand and master the shortcut keys of the control system. This article lists the most frequently used shortcut keys in our daily use. 1. Super key GNOME shor

Commonly used shortcut keys for moving the cursor in linux Command lines I am not very familiar with linux. I used to move the cursor one by one when I typed commands in linux. There are several common shortcut keys. For more detailed shortcuts, please slam the link below Http://coderbee.net/index.php/linux/201304