When a new customer is added to the table, a new row is created, and the data for that customer is stored in the corresponding columns of the new row. Each entry in a customer table is equivalent to a row in a spreadsheet, and each column contains the data for each customer (name, address, telephone, etc.). Once again, consider the spreadsheet analogy described earlier in this chapter. Each row, in turn, consists of the columns of data associated with the saved record. Therefore, a column designed to store numbers would be defined as containing numerical data.Įach new record saved to a table is stored in a row. For example, a table’s name, address, and telephone data fields are all columns.Įach column, in turn, is defined to contain a certain type of data. It is helpful at this stage to begin viewing a database table as similar to a spreadsheet where data is stored in rows and columns.Įach column represents a data field in the corresponding table. Schemas are also used to define the structure of entire databases and the relationship between the various tables in each database. For example, the table schema for a customer database table might define the customer name as a string of no more than 20 characters long and the customer phone number is a numerical data field of a certain format. The full book contains 94 chapters and over 830 pages of in-depth information.ĭatabase Schemas define the characteristics of the data stored in a database table. You are reading a sample chapter from Android Studio Giraffe Essentials – Kotlin Edition.īuy the full book now in eBook (PDF) or Print format. A table name, once assigned to a table in one database, may not be used for another table except within the context of another database. The same database may also include a products table used to store the product descriptions with associated product codes for the items sold by the business.Įach table in a database is assigned a name that must be unique within that particular database. For example, a database may contain a customer table that contains the name, address, and telephone number of each of the customers of a particular business. Each database can contain multiple tables, each designed to hold information of a specific type. Understanding Database Tablesĭatabase Tables provide the most basic level of data structure in a database. Before delving into the specifics of SQLite in the context of Android development, however, a brief overview of databases and SQL will be covered. This chapter will cover the SQLite database management system bundled with the Android operating system and outline the Android SDK classes that facilitate persistent SQLite-based database storage within an Android application. With the ever-present risk that the Android runtime system will terminate an application component to free up resources, a comprehensive data storage strategy to avoid data loss is a key factor in designing and implementing any application development strategy. The importance of persistent data storage becomes even more evident when considering the transient lifecycle of the typical Android application. The use of databases is an essential aspect of most applications, ranging from almost entirely data-driven applications to those that need to store small amounts of data, such as the prevailing game score. Mobile applications that do not need to store at least some persistent data are few and far between.
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