Creating a table in the MySQL database Create Table

Databases, as options for the concentration of information, are vital, and without them even a minor project does not do. The structure is well thought out, the tables are correctly designed, the connections are configured - the speed of information retrieval / recording depends on this, the reliability of data storage, the guarantee of the inability to accidentally cause damage, the availability of rollback, the completion of each transaction - and success in general.

The database, first of all, is a conceptual idea, the presentation of information and the logic of its use in a particular task.

Simple relationships = effective implementation

Relational ideas of data organization are clearly not the best, but they confidently hold their positions for many decades. As factories for the production of products and essential goods for people's consumption, they are certainly necessary.

Revolutionary ideas in the information business have repeatedly stated their right to life, but to this day could not provide significant evidence of the existence of such a right. As always, simplicity is the key to success. However, the topic of relations and links between information objects - points and systems in the information space - is still full of blank spots and interesting surprises.

Using a simple MySQL create table construct leads to the formation of simple and easy-to-use dozens of tables that formalize the scope of the task. Start using "muscle" is very simple, but after the first ten tables, relational relationships give rise to a different attitude to information, its presentation, storage and use.

Temporary, controlled and permanent

A characteristic point: the "fundamental construction" of the concept of databases cost without the participation of MySQL, which came to life with Internet programming and became its essential part. Dynamic modern technologies have allowed this database to become fast, reliable and efficient, easy to learn and use.

In addition to the basic tables, the create temporary table MySQL project provides the programmer with the ability to create temporary data structures that exist during the current session, the visit of a particular user, and the appearance of a specific event.

If before the tables and connections between them were treated as something unshakable, today even powerful databases are not accepted as fundamental objects. This is just a step to understanding the information structure needed to solve the problem.

By providing a tool to create temporary tables create temporary table, MySQL makes it possible to divide the database into static and dynamic components. By specifying the table field types, the programmer can automatically control the correctness of its formation. Using the MySQL create table check design, the developer can specify the conditions for filling the fields. Although this option is more likely to facilitate the migration of SQL constructs from other dialects.

Information space: points and systems

Each project, whether it is an entire site, a single page or one simple algorithm, is located in a certain place in a certain information space. The "address" of this place is a specific task, the conditions for the existence of the algorithm: the information structure at the input and output, the transformation forms in the process.

However, it is not necessary to follow the rules of MySQL, create table can create not at all what is provided by its syntax.

In this example, the code_back, owner_code, and session_code fields define the keys respectively for the return, client, and session. Not only the use of a non-standard version of MySQL create table, key here does not lie in its area of competence, but is written according to the meaning: the return code in case of a non-completion of the transaction, the code of the active client and the session code, which may be several for this client, Where the return code will go to control.

It is also non-standard to use the fields h_code, a_contents and a_surprise. Here in create table MySQL is an example of how one field can contain not data, but semantics. In any situation, when you need to have a client table, it is reasonable to create a cache of the active part of this table. In this case, it is not necessary to do this adequately to the original data structure. So, for example, the a_contents field will receive the content: name, password, e-mail, and a_surprise - the current state of the user.

The idea of a_contents and / or a_surprise

Such an option does not require access to the main table, which can be large and cumbersome, but will allow you to confine yourself to a small table that contains only up-to-date information. Here, create table MySQL is an example of what you can do by entering a client name and password, or a password and an e-mail in a simple condition: (a_contents like '{$ cUserName}; {$ cUserPass}%') or (a_contents like '% {$ CUserPass}; {$ cUserName} ').

This example uses its own function to check the presence of the table: scTableExists ('rm_cache') because if the table does not exist, you will need to not only create it, but also record, for example, several initial records with the resource administrators' data.

Standard option create table if not exists MySQL offers a limited version for checking the existence of a table and creating it in case of absence. Usually this is not enough. It is necessary not only to check the availability of the table, but also to fill it with the initial information.

Cell of a simple type

The specificity of MySQL's usage languages, in particular PHP, traditionally minimizes the amount of popular data: first of all, the untypedness of its variables. Most often, lines are used, as necessary - numbers and dates, sometimes logical data. More extensive data description features on MySQL create table rarely contains. Although the latter is determined by the problem to be solved. It is possible to use the entire range of data through create table MySQL, an example is any modern content management system.

What and how to use - defines the developer. At the moment, according to wikipedia, the voluminous and high-speed capabilities of MySQL can satisfy the most capacious imaginations of the customer, taking into account the experience of the developer used. When used on MySQL create table default-constructs allow you to create clean (empty tables) with cells of variable length and create dynamic content in the process.

Complex data structures

Orientation to simple data types, primarily lines, led to an increase in interest in the construction of complex information objects, which, when working with the database, is converted into storing mostly strings, numbers (indexes - most often), dates and "large data" - pictures , Sounds, other capacious content. Here the dialect of create table SQL MySQL practically does not limit. With all the simplicity and availability of the "muscle", the programmer has at his disposal all the power of the real SQL language.

Externally simple cell from the point of view of the database, the type char or varchar turns into an algorithm when reading into a complete object - a complex data structure (properties and methods, syntax and semantics), and when writing again, it turns into a compact form, the essence of which is determined by the developer.

Elementary table

Only columns, only lines and only one element at their intersection, and only one type is a cell. This is the basic rule of MySQL's "create table". No type of MySQL data is original: numbers, character strings, dates ... It does not follow from the syntax, but so it turns out in practice.

A programmer, interpreting a cell, can admit in it an object of any type, conditioned by the requirements of the problem. From the perspective of the database, this "any type" is just a line.

However, it does not matter what and how the developer prefers to use. It is important that at the moment of time (according to Wikipedia) the volumetric and high-speed parameters of MySQL can satisfy the most capacious imaginations of the customer taking into account the experience of the developer used.

"Living" are the simplest tables, arranged in the simplest possible way. If the developer puts the proper meaning into each field, putting it into a char or varchar type within the MySQL create table syntax, the table will work.

An integer table

It is worthwhile to talk separately about indexes in MySQL. Create table allows you to immediately describe and use them to access large amounts of data. This approach is very explainable, customary and worked out to such trifles that optimization rests on the processor speed, sample caching, cunning algorithms for counting, frequently selected data, editing of php.ini, my.ini and httpd.conf.

Meanwhile, no one interferes with the developer to create his own view of "data" - "keys to data", for simplicity, integer - not a single line in the table, only numbers. The microproject create table int MySQL will provide all the rest of the tables: quick access, simple operations, full functionality at an ideal speed.

Whole numbers, organized as a map of real data in large and cumbersome tables, without problems will speed up the selection and modification of information. It is not necessary to create such a key access option for the whole time, you can use the create temporary table construct, MySQL will create a temporary table before using it. Or, for example, for each user - its own key table.

In this context, the syntax is not a designated use. Create table if not exists MySQL allows you to create the required tables even if they are unexpectedly missing: for example, there was an incorrect entry / exit or computer failure, and the indexing was broken.

The realities of hosting are MySQL +

Historically, the database was a meaningful data structure. The construction of M ySQL create table initially adhered to the classical representations about data and their place on the disk space. Internet programming, and especially the hosting options and the logic of popular site management systems, made a strange, at first glance, bias: one database can be a collection of several. The division is based on the prefixes of the table names.

Some hosting providers have imposed their requirements on database names, for example, the name of the database begins with the name of the owner of the hosting.

By and large, it does not matter how to name the database and how to name its tables. However, the current situation began to represent not just the syntax of MySQL, but the hosting requirements plus the syntax, that is, MySQL +.

The smaller the table, the simpler it is, and the fewer entries in it, the more densely it is implanted into the programming language through which the necessary actions are performed with the data.

In principle, any problem can easily be described as elementary components, the only question is how much this simplicity will cost.

If you need a pure MySQL, then it's your own hosting, your own server, where there will be no restrictions either on the number of databases, nor on the rules for naming them and their tables.

Variety of versions of Apache / MySQL / PHP

Dependence on hosting conditions is not so much a problem as an important condition for modern secure programming. You can write in PHP 7.0.13, use MySQL 5.7.16, but the customer will have a hosting that allows only Perl and the version of "muscle" 4.1.1 or an outdated version of PHP.

Basically (which, incidentally, is not a fact), hosting is provided on Linux, FreeBSD, UBUNTU and other variations of Unicos-like systems. All of them work fine, but each of them has its own features, its variants of AMP assemblies (Apache, MySQL, PHP). Not always and not every team will work in the next version, although it worked in the previous one.

Such a simple operation as exporting a database any version of MySQL does without any problems, both from phpMyAdmin and from the command line. A reverse import operation may not take place. Most often you will have to change something in the settings of PHP, MySQL server or Apache. If the changes do not help, you'll have to look for alternatives.

Obvious fact, another operation can be performed by reinstalling the database, programming language or server. This is not the best solution, but, as a rule, effective.

Database creation / verification table

The MySQL create table syntax is rarely applicable in its standard version. If it is not considered in the context of popular site management systems: there will always be a classic of the genre. In everyday work, it's easiest to consider it in the context of practice: what fields are needed in the table, what type and size they should have. The rest still have to be finalized in the development process: a set of characters, sort order, keys.

Optimal is a variant of the algorithm, in which even the absence of a database does not prevent the site from getting started. You can write your own function for checking the availability of a database and / or a table, when you need to create not only information structures, but also fill them with initial information.

Often enough to use a series of constructs Create table if not exists, MySQL then will not surprise the owner of the site or his visitor with the fact that he unexpectedly reports: there is no database, or the structure of the tables is broken.

In modern programming, the general rule of "trust, but verify" does not work, rather it will use the "check and use" logic.

Create table: MySQL sample user table

Registration of new visitors and input / exit of the users of the site are developed numerous times, but there is no limit to perfection in this important part of any site yet.

In many respects, the entrance / exit and registration are determined by the scope of the site and / or the site management system used, but more often - the desire to develop something more secure, protect user accounts, prevent the hacking of the site.

Typically, the MySQL database is more secure than the site, but in case of a failure, it is possible to display the browser in the error messages of the site configuration code containing the names and passwords to the database.

Good practice is to divide the data into static and dynamic components. Using the user table as an example, you can have a large users table and active cache_users. The first table contains a large number of users, the second - only those who worked in the last 24 hours (for example). Any new user that is not in the second table, comes there after logging in / logging and is stored for a while.

But the division into two tables here gives not only the speed of data sampling (a small table is always faster and cumbersome and large), but also that it contains only the information that is needed most often when any client of a particular site is running. For sampling or changing data, naturally, the main table is used.

Memory, information and databases

In the field of information technology somehow it did not turn out to be a programming language with memory. Language - a variable, constants and constructs that allow something and somehow manipulate. The database is something that stores it. From it you can always choose something in it, you can write something down.

The language and the base for the purposes of working with information are combined, but the logic of the relationships in this triad is not so perfect, even as in a simple AMP: Apache, PHP, MySQL. Here everything is clear: the server, the programming language and the database are all that is needed for an overwhelming number of tasks.

The SQL language is the same programming language, and generally the database has its own logic of operations, its own programming concept. Here, the desire of the database for programming is evident. PHP is a good tool, but to say that it adequately tends toward databases is difficult. However, its designs and functions are developing and improving.

If you combine PHP and MySQL into a single whole, you will get a tool with memory. The option of combining gives the idea of object-oriented programming: the object described in the language, for the time of its uselessness is in the memory (in the database) in a compact state. When it becomes necessary, it is restored to a full-fledged object and acts in accordance with its competence.