<p>In Oracle, what is the difference between :</p>

<pre><code>CREATE TABLE CLIENT
(
 NAME VARCHAR2(11 BYTE),
 ID_CLIENT NUMBER
)
</code></pre>

<p>and</p>

<pre><code>CREATE TABLE CLIENT
(
 NAME VARCHAR2(11 CHAR), -- or even VARCHAR2(11)
 ID_CLIENT NUMBER
)
</code></pre>

[{'answer_id': 81465, 'author': 'Matthias Kestenholz', 'author_id': 317346, 'author_profile': 'https://Stackoverflow.com/users/317346', 'pm_score': 5, 'selected': False, 'text': '<p>One has exactly space for 11 bytes, the other for exactly 11 characters. Some charsets such as Unicode variants may use more than one byte per char, therefore the 11 byte field might have space for less than 11 chars depending on the encoding.</p>\n\n<p>See also <a href="http://www.joelonsoftware.com/articles/Unicode.html" rel="noreferrer">http://www.joelonsoftware.com/articles/Unicode.html</a></p>\n'}, {'answer_id': 81469, 'author': 'Seldaek', 'author_id': 6512, 'author_profile': 'https://Stackoverflow.com/users/6512', 'pm_score': 2, 'selected': False, 'text': '<p>I am not sure since I am not an Oracle user, but I assume that the difference lies when you use multi-byte character sets such as Unicode (UTF-16/32). In this case, 11 Bytes could account for less than 11 characters.</p>\n\n<p>Also those field types might be treated differently in regard to accented characters or case, for example \'binaryField(ete) = "été"\' will not match while \'charField(ete) = "été"\' might (again not sure about Oracle).</p>\n'}, {'answer_id': 81492, 'author': 'David Sykes', 'author_id': 3154, 'author_profile': 'https://Stackoverflow.com/users/3154', 'pm_score': 9, 'selected': True, 'text': '<p>Let us assume the database character set is UTF-8, which is the recommended setting in recent versions of Oracle. In this case, some characters take more than 1 byte to store in the database.</p>\n\n<p>If you define the field as <code>VARCHAR2(11 BYTE)</code>, Oracle can use up to 11 bytes for storage, but you may not actually be able to store 11 characters in the field, because some of them take more than one byte to store, e.g. non-English characters.</p>\n\n<p>By defining the field as <code>VARCHAR2(11 CHAR)</code> you tell Oracle it can use enough space to store 11 characters, no matter how many bytes it takes to store each one. A single character may require up to 4 bytes.</p>\n'}, {'answer_id': 81714, 'author': 'user15453', 'author_id': 15453, 'author_profile': 'https://Stackoverflow.com/users/15453', 'pm_score': 4, 'selected': False, 'text': '<p>Depending on the system configuration, size of CHAR mesured in BYTES can vary. In your examples:</p>\n\n<ol>\n<li>Limits field to 11 <b>BYTE</b></li>\n<li>Limits field to 11 <b>CHAR</b>acters</li>\n</ol>\n\n<p><hr/>\nConclusion: 1 CHAR is not equal to 1 BYTE.<br/><br/></p>\n'}, {'answer_id': 67398489, 'author': 'Aman Singh Rajpoot', 'author_id': 12937828, 'author_profile': 'https://Stackoverflow.com/users/12937828', 'pm_score': 1, 'selected': False, 'text': '<p>In simple words when you write <code>NAME VARCHAR2(11 BYTE)</code> then only 11 Byte can be accommodated in that variable.</p>\n<p>No matter which characters set you are using, for example, if you are using Unicode (UTF-16) then only half of the size of Name can be accommodated in <code>NAME</code>.</p>\n<p>On the other hand, if you write  <code>NAME VARCHAR2(11 CHAR)</code> then <code>NAME</code> can accommodate 11 CHAR regardless of their character encoding.</p>\n<p><code>BYTE</code> is the default if you do not specify <code>BYTE</code> or <code>CHAR</code></p>\n<p>So if you write <code>NAME VARCHAR2(4000 BYTE)</code> and use Unicode(UTF-16) character encoding then only 2000 characters can be accommodated in <code>NAME</code></p>\n<p>That means the size limit on the variable is applied in <code>BYTES</code> and it depends on the character encoding that how many characters can be accommodated in that vraible.</p>\n'}]
['https://Stackoverflow.com/questions/81448', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/12388/']