A data item is a single unit of data in a storage record. This term may refer specifically to the smallest possible unit of information, or more generally to a single entry or field. The context usually provides information about the meaning. Data items are stored in computer databases in a variety of ways and may be secured to restrict access or left unsecured to make them readily available to anyone who wishes to access them.
When it is the smallest possible unit of meaningful information, it represents a very small component of a larger set of data. In a census database, for instance, data items can include things like names, ages, and components of addresses. In an address, each part of the address is its own data item and can be looked at separately. Other usages of the term may lump anything in a given field under the heading of a single data item, in which case a whole address line would be a data item.
Binary code is used to store information in databases in a meaningful, readable, and easily retrieved way. File sizes can vary depending on the kind of information stored inside the database and the format. The more clarifying information is added, the larger the file will be, as it needs to contain not just the data, but also the information about the data. In an encrypted database, the information is made confidential so only a person with the right key can access it.
Within a database, it is necessary to use the correct format for inputting and storing data items. Mistakes and irregularities can make the database more difficult to use. For example, when entering dates, users need to be consistent about how they order the information in a date so conflicting entries don't occur. Users may be instructed to code information in a specific way at the time of input so it will be readable by other users in addition to being searchable.
Database corruption can be a cause for concern. A corrupted data item may be incorrect or missing. A consistent storage and ordering system can be helpful for the identification and isolation of corruption. If users can quickly spot a problem with the database, they can intervene before it spreads or causes errors. Corruption may be the result of a virus, hacking, incorrect shutdown or saving technique, or another problem. It is important to identify the cause while addressing the problem.